The Early Stages in the Evolution of The Wars of the Lord

THE JEWISH QUARTERLY REVIEW, LXXXVII, Nos. 1-2 (July-October, 1996) 1-46

THE EARLY STAGES IN THE EVOLUTION OF GERSONIDES' THE WARS OF THE LORD1

RUTH GLASNER, Hebrew University

ABSTRACT

The aim of the paper is twofold: first, to follow the evolution of Gerson- ides' book The Wars of the Lord, and the development of his cosmology during the years 1321-1328; and second, to show to what extent Gersonides' cosmology and physics were determined by his astronomy. By examining the references to the Wars in the early works of Gersonides (mainly the commentaries on Averroes' commentaries on the physical books ofAristotle, dated 1321, and also the commentary on Job from the end of 1325), the paper follows the development of Gersonides' ideas during these years. By 1321 Ger- sonides was acquainted with al-Bitriiji's criticism of Ptolemy and with his alternative astronomical models and he severely criticized al-Bitriuji's efforts. Learning from al-Bitriiji's errors, Gersonides developed his empirical methods and an alternative astronomy, accepting the eccentric model but rejecting the epicyclic. The attempt to justify his astronomical models led to his original cosmology, which differs significantly from Aristotle's.

11 would like to thank warmly Prof. B. R. Goldstein and Prof. J. L. Mancha for reading a first draft of this paper and for their helpful comments and corrections, particularly on the subject of the chronology of Gersonides' astronomical work, and Dr. Gad Freudenthal for reading the paper, for his relevant observations and suggestions and for allowing me to use a preliminary version of his edition and translation of V.1.43 of the Wars. I am much indebted to the Sidney M. Edelstein Center for the History and Philosophy of Science, Technology and Medicine and particularly to Dr. Yemima ben Menahem for making this research possible.

References to The Wars of the Lord are cited by book (ma'amar) in Roman numerals followed by part (heleq) and chapter (pereq) in Arabic numerals. Numbers following these citations refer to folios of manuscripts (or pages of edition) and lines, thus Q 56b19 = MS Q, f. 56b, line 19; or G 231,38-40 = B. R. Goldstein, The As- tronomy of Levi ben Gerson, p. 231, lines 38-40. (Note: Goldstein's Hebrew text, coming at the end of an English book, follows a reverse pagination, e.g., Wars V.1.3, G 301,4-300,12.) The following abbreviations are used:

IMHM = Institute of Microfilmed Hebrew Manuscripts. G = B. R. Goldstein, The Astronomy of Levi ben Gerson (New York, 1985). In-

cludes edition and translation of V.1.1-20. P = Book V.1, MS Paris, Bibliotheque Nationale h6b. 724 (IMHM 11612). Q = Book V.1, MS Paris, Bibliotheque Nationale h6b. 725 (IMHM 11613). L = ed. Leipzig, 1866 of Wars of the Lord (own nmnnn 'io, Milchamot Ha-schem:

Die Kdmpfe Gottes).

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2 THE JEWISH QUARTERLY REVIEW

The making of Gersonides' (1288-1344) major book The Wars of the Lord was a long and complex process. I shall roughly distin- guish four stages in its evolution.

(1) The early version. Gersonides tells us that he started to work on the Wars in 1317.2 The book is often referred to in his commentaries on the physical writings of Averroes, completed in 1321.3 These references indicate that there was an early version of the Wars, which, as far as we know, is no longer extant. We do not know whether the version was only for Gersonides himself or whether it was accessible also to students or friends.4

In the earliest of Gersonides' super-commentaries, that on Aver- roes' epitome of Aristotle's Physics, dated June 1321, there are two references: the first mentions explicitly "our book The Wars of the Lord"; the second is in the colophon, where Gersonides explains that he did not deal with the subject of the eternity of the world when commenting on the passages in which Aristotle develops this theory, because "we have already done this in a book especially dedicated by us to this investigation" (mpnn mn5 i)5 'mrn-1n Iv).5 This sentence suggests that the book originated as a monograph on the subject of the eternity of the world, i.e., as Book VI. 1 of the extant version.6 However, the references to the early version are not only to the material of VI. 1, but also to material included in the three parts of the present Book V. (Book V.1 is a treatise on mathematical astronomy; V.2 is on cosmology; V.3 is cosmological-theological, dealing with the celestial movers.)

(2) The addition of thefirstfour books. In 1324 Gersonides completed the systematic project of commenting on the works of Aver-

2Wars VI.1, colophon, L 417. 3The references are listed in the Appendix below, pp. 42-46. 4In the colophon of the commentary on the Epitome of the Physics, Gersonides re-

fers to the early version as nvrpnn nlm5 l)) -mril it'. Touati and Feldman understand ri3 inv,o as indicating that the book was not distributed. As I understand this sentence -rlmo describes orrpnn nNr, rather than l)5. In this case the phrase does not mean that the book was intended only for private use. C. Touati, La pense'e philosophique et the6ologique de Gersonide (Paris, 1973) 49; S. Feldman, trans., The Wars of the Lord, Levi ben Gershom (Gersonides) (Philadelphia, 1987) 1:55.

5Both references are listed in the Appendix. 6It should be noted that Gersonides refers to "an investigation on the subject of

the eternity of the world," not to "a treatise on creation." We shall see later that there are no early references to Book VI.2.



GERSONIDES' THE WARS OF THE LORD-GLASNER 3

roes. Probably about that time, or somewhat later, he started to work on his biblical commentaries. The references in the early biblical commentaries indicate that by 1325 the first four books of Wars had been added, and the work was subdivided into books (maDamarim) and parts of books. In the commentaries on De anima, Parva natu- ralia, and the commentary on the letters of Averroes, written between December 1323 and February 1324, there are only unspecified references to Book VI. 1.7 In the earliest of the biblical commentaries, the Commentary on Job, concluded December 1325, Gersonides refers seven times to the fifth book (one reference is specifically to the third part of the fifth book). He also refers five times (without men- tioning book number) to the first four books, once to the fifth book, and once to the sixth.8 The first explicit reference to book number other than the fifth is to the fourth book in the Commentary on Qohelet from 1328.9

(3) The completion of Gersonides' cosmology and theory of creation. In the colophons of the extant version of Wars, the three parts of Book V and Book VI are dated from November 1328 to January 1329. These dates mark the completion of the fifth and sixth books, and of the whole work, with the exception of V.1.

(4) The continued work on Book VI. In the colophon of V.1 of the extant version, Gersonides notes that he added several things (on2m nhp) after the date indicated, in accordance with his later observations.10 In chapter 46 he states:

For we did not determine the position of the mean sun perfectly until the year 1335 according to the Christian reckoning.... Much before that time this book was already completed.... Subsequently, when our eyes were opened by [further] observations and we obtained [what was required for] a more perfect statement of the matter, we went over the

7 There are partial critical editions of these texts. I have consulted also Oxford Bod. MS 1373 (IMHM 22397) which includes the three texts. The references are on fols. 247a6-12 and 258bl7-18.

8Commentary on Job (Ferrara, 1477). Reference to the first four books: fol. 3b (to Wars 1.6, perhaps also 11.3), 21a, 43a, 95a-b, 96a (all to 111.4); to book V: fols. 9a (explicitly to the third part of Book V, probably to chapter 8), 26b (book number not mentioned, but it is to V.3.5), 40b, 44b, 59b, 60b-61a, 70a, 10lb-102a (all explicit references to the fifth book); to Book VI: fol. 107b (to VI.2.8).

9 Commentary on the Five Scrolls (Riva di Trento, 1560), fol. 35b col. al. See also Feldman, The Wars 1:56.

10Following ch. 136, P fol. 257b12-15.




contents of this book and perfected whatever needed perfecting. There- fore, you will find many observations in this treatise that we made after the completion of this book. "

Book V.1 in the extant manuscripts is not complete, and perhaps was never completed. 12 Goldstein comments that the majority of Ger- sonides' observations are dated between 1330 and 1339, "but they are so woven into the text that 1328 must be taken as the date of a preliminary draft, and not of a completed text to which a few remarks were later appended." 13 Mancha argues that many chapters of the extant version were written after 1334, some of them after 1339. 14

The writing of the Wars, according to this brief summary, lasted at least 22 years, the history of Book V.1 being the longest and most complex. In what follows I shall concentrate on the first stage-the early version. I shall try to identify, following the references in the commentaries, the subjects that were included in this early version. When I refer to chapter numbers of the extant version I mean that subjects discussed in these chapters were part of the early version, not that these chapters in their present form are early. This study also leads to interesting conclusions concerning the evolution of Ger- sonides' methods and ideas, and shows to what extent his astronomy and natural philosophy are interrelated. In section IV of this paper I deal with the third stage-the completion of Book VI and the cosmological-theological parts of Book V.

The method I use for learning about the early version of the Wars and about the evolution of Gersonides' ideas is to examine his commentaries for both explicit references and passages that do not mention the Wars, but indicate that certain subjects discussed in the Wars occupied Gersonides' mind at an early stage. I rely mainly on the supercommentaries on the physical commentaries of Averroes, all dated 1321, but also on the early biblical commentaries. Is this method sound?

" Wars V.1.46, Q fols. 66a34-b3 (translation from B. R. Goldstein, "A New Set of Fourteenth-Century Planetary Observations," Proceedings of the American Philosophi- cal Society 132 (1988) 387.

12B. R. Goldstein, "Preliminary Remarks on Levi ben Gerson's Contributions to Astronomy," The Proceedings of the Israel Academy for the Sciences and Humanities 3 (1969) 250.

13 Ibid., 253. 14 J. L. Mancha, "The Provencal Version of Levi ben Gerson's Tables for Eclipses,"

forthcoming in Archives internationales d'histoire des sciences.




As already mentioned, Gersonides had greatly modified the astronomical part of the Wars (V.1) after the date given in the colophon (Nov. 1328). Mancha concludes that if the date marked in the colophon indeed indicates that Gersonides completed a version of V. 1 by this time, then that version was entirely different from the extant one known to us. Sirat, who studied the manuscripts of the Wars, asks whether it is likely that Gersonides did not modify the philosophical parts of the Wars too, but she does not give a conclusive answer. 15 Freyman, studying the manuscripts and the printed editions of the Commentary on the Pentateuch, was led to suspect that there was more than one version. He suggests that long after having com- posed the commentary, Gersonides introduced additions, which were probably marginal. This way two versions were disseminated and eventually, through the process of scribal copying, different combi- nations of the two versions were formed. 16 Manekin shows that there are two groups of manuscripts of The Correct Syllogism, which "rep- resent two 'editions' of the text, the second edition representing a major revision of the first." The completion date is 1319 in both groups of manuscripts, yet Manekin shows that the second edition is certainly later, and the first edition also includes a reference to the Commentary on the Prior Analytics, dated 1323.17 Referring to the colophon dates of Gersonides' commentaries, Manekin comments (attributing this point to Freudenthal) that "these are completion dates and that the actual writing occurred over a long period of time. Gersonides often wrote different works simultaneously, which would account for the cross references and the close completion dates." 18 S. Harvey, discussing a certain passage from Gersonides' Commen- tary on the Middle Commentary on the Physics suspects that the two (conflicting) parts of the passage might have been written at different times. 19

Taking into account these suggestions concerning Gersonides' "writing habits," one should ask to what extent Gersonides' colophon

15 C. Sirat, "La tradition manuscrite des Guerres du Seigneur," in Gersonide en son temps, ed. G. Dahan (Louvain, 1991) 302.

16E. Freyman, "Les commentaire sur le Pentateuque de Gersonide: 6ditions et manuscrits" in Gersonide, ed. Dahan, 126, 130.

17C. H. Manekin, The Logic of Gersonides (Dordrecht, 1992) 38-41. '8Ibid., 14. 19 S. Harvey, "Did Gersonides Believe in the Absolute Generation of Prime Matter?"

(Hebrew), Jerusalem Studies in Jewish Thought 7 (1988) (= Shlomo Pines Jubilee Vol- ume, Part I) 314.




dates are reliable. In the case of the present study this question concerns mainly the dates of the supercommentaries on Aristotle's major physical treatises. In the course of my work on these commentaries I did not find evidence that they were "updated." Several of the themes that I suggest were part of the early version are referred to in several passages in more than one commentary. 20 In cases of doubt I checked all extant manuscripts. I tend to believe, therefore, that the evidence is trustworthy, and that the methodology I propose is indeed sound.

I. GERSONIDES' TWO MAJOR PROJECTS

According to the brief description offered above, the Wars began and ended with Books V and V.1. Gersonides was indeed engaged for many years in working on two major questions which had baffled Maimonides, and to which Maimonides had not given a decisive answer: the question of the eternity of the world and the question of the incompatibility between astronomy and natural science. Both questions were considered to be beyond the capacity of human understanding.21 Gersonides' first, philosophical-theological, project resulted in his theory of creation, which is presented in the sixth book of the Wars; his second, astronomical, project-finding a true description of celestial movements and of the structure of the heavens, which would account for the observed phenomena and would be compatible with natural science-resulted in the first part of the fifth book. This fact is by no means accidental. Gersonides strongly emphasized that the order of presentation is very important.22 Gold-

20 Mainly the arguments for the justification of the eccentric model, described below in sections 111.2 and 111.3.

21 On the difficulty of the first task, Gersonides comments in the Wars, Author's Introduction, L 4 (Feldman, The Wars 1:94); V.2.1, L 189; VI.I.1, L 293-294. As to the difficulty of the second task see: V.1.3, G 301-297, note especially 300,12; Mai- monides, Guide 2.24 (Pines' English translation [Chicago, 1963], 2:327). On the position of Maimonides see Y. T. Langermann, "The True Perplexity of the Guide of the Perplexed" in Perspectives on Maimonides: Philosophical and Historical Studies, ed. J. L. Kraemer (Oxford, 1991) 159-174, especially 162-168.

22 Wars, Author's Introduction, L 10 (Feldman, The Wars 1: 103). On this subject see S. Pines, "Appendix: Problems in the Teachings of Gersonides" (Hebrew) in Mehqa- rim be-Qabbalah, be-Filosofiah Yehudit, uve-Safrut ha-Mussar weha-Hagut (Jerusa- lem, 1986) 448-449.




stein observes, "Levi clearly intended his readers to be familiar with his astronomy before continuing with the later parts of book V and book VI."23 Though essential for understanding the Wars, the astronomical part was not included in the two printed editions, is extant in only a few manuscripts, and remained virtually unknown. Only re- cently, following the studies of Goldstein, has this part of the Wars become more accessible. In what follows I shall emphasize the close relationship between Gersonides' astronomy, cosmology, and theory of creation, particularly the influence of his astronomy on his natural philosophy and theology.

II. THE FIRST STEPS OF THE ASTRONOMICAL PROJECT:

THE ARGUMENT WITH AL-BITRUJI AND THE

COMMITMENT TO THE ECCENTRIC MODEL

Recent research has emphasized that Gersonides' realistic attitude and his empirical approach and methods were uncommon.24 Con- sidering that he was a Jew, Gersonides' originality was even more remarkable. Freudenthal regards Gersonides' interest in the mathematical sciences per se as exceptional among his fellow Jews.25

What led Gersonides to adopt his unusual realistic attitude and his empirical methods? Gersonides himself answers this question: "The arguments of the physicists against Ptolemy's model brought this question to our attention" (the whole passage is quoted below, section 11.1). The question is that of the adequacy of Ptolemy's models,

23 B. R. Goldstein, "Astronomical and Astrological Themes in the Philosophical Works of Levi ben Gerson," Archives internationales d'histoire des sciences 26 (1976) 222; reprinted in B. R. Goldstein, Theory and Observation in Ancient and Medieval Astronomy (London, 1985), ch. 23 (emphasis mine).

24 B. R. Goldstein, The Astronomy of Levi ben Gerson (New York, 1985) 9; "The Status of Models in Ancient and Medieval Astronomy," Centaurus 24 (1980) 142; H. Hugonnard-Roche, "Problemes m6thodologiques dans l'astronomie au debut du XIVe siecle" in Studies on Gersonides, a Fourteenth-Century Jewish Philosopher- Scientist, ed. G. Freudenthal (Leiden, 1992) 70; G. Freudenthal, "Epistemologie, astronomie et astrologie chez Gersonide," Revue des etudesjuives 146 (1987) 359.

25 G. Freudenthal, "Les sciences dans les communaut6s juive medi6vales de Pro- vence: leur appropriation, leur role," Revue des etudesjuives 152 (1993) 124; "Sauver son ame or sauver les phenomenes" in Studies on Gersonides, ed. G. Freudenthal, 317-352; "Human Felicity and Astronomy: Gersonides' Revolt against Ptolemy" (Hebrew), Dacat 22 (1989) 55-72.




and the reference is apparently to the Andalusian criticism on Ptole- maic astronomy.26

Gersonides was certainly acquainted with Averroes' and Maimon- ides' arguments against Ptolemy. Al-Bitrtiji, however, not only criticized Ptolemy but also tried to construct a new astronomical model without using classical eccentrics and epicycles. His "new astronomy" was the main outcome of the Andalusian revolt, but by no means offered a serious alternative to Ptolemy. Although his "new astronomy" was not satisfactory, Saliba states: "Bitriujl made the re- form of Ptolemaic astronomy a necessity. After Bitriiji no astronomer could tolerate the Almagest's problems without any criticism."27 This comment certainly applies to Gersonides. Al-Bitrtiji's "realistic exercise," though unsuccessful, was relevant for Gersonides, who was both an astronomer and a philosopher (and who was intrigued by Maimonides' agnostic attitude).28

Al-Bitriji's book On the Principles of Astronomy was translated into Hebrew and Latin, and was fairly well known. 29 Gersonides was acquainted with it by 1321;30 he was also familiar with Ptolemy's

26 Concerning the Andalusian revolt see A. I. Sabra, "The Andalusian Revolt against Ptolemaic Astronomy: Averroes and al-Bitr-uj"l in Transformation and Tradition in the Sciences: Essays in Honor of L B. Cohen, ed. E. Mendelsohn (Cambridge, 1984) 133- 153; Freudenthal, "Human Felicity," 65-67; "Sauver son ame," 336-338.

27 G. Saliba, "The Development of Astronomy in Medieval Islamic Society," Arab Studies Quarterly 4 (1982) 211-225; reprinted in G. Saliba, A History of Arabic As- tronomy: Planetary Theories during the Golden Age of Islam (New York, 1994) 63.

28 As to the impact of Gersonides' being both an astronomer and a philosopher see G. Freudenthal, "Rabbi Lewi ben Gerschom (Gersonides) und die Bedingungen wis- senschaftlichen Fortschritts im Mittelalter: Astronomie, Physik, erkenntnistheore- tischer Realismus und Heilslehre," Archiv fiir Geschichte der Philosophie 74 (1992) 175-179.

29 Al-Bitriiji's book was translated into Hebrew in the middle of the thirteenth century by Moshe ibn Tibbon. Goldstein published the Arabic text, a critical edition of the Hebrew, and an English translation with introduction and notes: B. R. Goldstein, Al-Bitriujl: On the Principles of Astronomy (New Haven, 1971). The book was translated into the Latin by Michael Scott. The Latin text was edited by F. J. Carmody, Al- Bitriji, De motibus celorum, Critical Edition of the Latin Translation (Berkeley, 1952). Carmody shows that the Latin translation attracted attention, and was influential in the thirteenth century. There is less evidence for the fourteenth (Carmody's introduction, 34-38). Goldstein shows that there are three references to al-Bitruji's book by Jews in the thirteenth and fourteenth centuries; by Yehuda ben Shlomo ha-Kohen, by Gerson- ides, and by Isaac Israeli (Goldstein's introduction, 40-45).

30He refers to al-Bitriiji's astronomy in the commentaries written in 1321: Com- mentary on the Epitome of De Caelo, MS Paris 919, ff. 200bl0- 1 and 201b24-26; Commentary on the Epitome of the Meteorology, MS Berlin 110, f. 11Gb col. b16-22.




Almagest and Planetary Hypotheses by that time.3" I shall suggest that he came to adopt his quite unusual realistic attitude and empirical methods while studying al-Bitruiji's criticism of Ptolemaic astronomy. Gersonides' arguments against al-Bitr-ujl are expounded in chapters 39-46 of Book V.1. In these chapters he often refers to methodological questions and formulates methodological principles. The inclusion of the "autobiographical" chapter 46 at the conclusion of this group of chapters, I believe, emphasizes the importance of the criticism of al-Bitr-ujl's "new astronomy" in the development of Gersonides' methods and attitudes.

Gersonides was most intrigued by the prospect of a "realistic astronomy" compatible with natural science, but he was fully aware of al-Bitriiji's failure to offer such an astronomy. He analyzes al- Bitriiji's failure and learns from his mistakes. Not the mistakes in the making of his model, which Gersonides dismisses right away,32 but al-Bitr-ji's false conceptions of the science of astronomy and of the role of the astronomer. I shall try to show in detail how al-Bit j-'s attempt and its failure affected Gersonides' attitude and methods as an astronomer and led Gersonides to develop his own "new astronomy," which was realistic in a new and more sophisticated sense than al-BitrujI's.

11.1 Gersonides' Argument with al-Bitritji: The Eccentric Model

For Gersonides the failure of al-Bitr-jW's "new astronomy" was the failure of the theoretical possibility of rejecting both of Ptolemy's models-the eccentric and the epicyclic. 33 This, I believe, is the key to understanding Gersonides' empirical approach. Thus interpreting al-Bitrtiji's failure, Gersonides was led to his own solution: the rejection of the epicyclic model and the adoption of the eccentric. This solution cannot be proved by theoretical arguments. Theoretical

31 He refers to Ptolemy's theories several times in the commentaries, e.g., Commen- tary on the Epitome of Generation and Corruption, MS Vatican 342, ff. 208a-b; Com- mentary on the Epitome of De Caelo, MS Paris 919, ff. 200b, 201b, 203a, 208b. In f. 203a he explicitly refers to Ptolemy's Almagest. In f. 168b he quotes a passage in which Averroes refers to Ptolemy (Averroes, Epitome of De Caelo, MS Paris 918, f. 55b col. a24-25) and adds that the reference is to the Planetary Hypotheses.

32Wars V.1.44, Q f. 62b37-63a3. See also Goldstein, "Preliminary Remarks," 246-247.

33 Gersonides states this explicitly in his commentary on De caelo. The passage is quoted below.




arguments led the Andalusians to reject both of Ptolemy's models. Gersonides' solution can be supported only by empirical evidence.

In chapters 39-46 of the astronomical part of the Wars, Gerson- ides discusses different aspects of the al-Bitriiji/Ptolemy controversy. In V. 1.43, he analyzes the arguments against Ptolemy's two models. The conclusion of his discussion is the adoption of the eccentric model and the rejection of the epicyclic. This group of chapters includes a great deal of late material, but also, as I shall try to show, an early "kernel" that was part of the early version of the Wars.

In the commentaries Gersonides mentions several times the eccentric and the epicyclic models. Some of these references are in conditional statements: "Levi said, if the sun had an eccentric sphere . . ."; "Levi said, . . . if it were true that the sun has eccentricity or an epicycle... ."34 In others, he ascribes them to Ptolemy: "the epicycle, assumed by Ptolemy"; "the sphere eccentric to the center of the world, according to the astronomy assumed by Ptolemy";35 "either you say the moving poles, following the master of new astronomy [al-Bitriiji] or there are eccentric spheres, encompassing or not encompassing the earth, as was assumed by Ptolemy."36

These references might indicate either that Gersonides did not want at that time to commit himself to Ptolemy's two models (or to one of them), or that in texts dealing with natural science he did not want to discuss astronomical questions. He remarks several times that the commentaries are not the proper place for mathematical dis- cussions,37 and it is likely that he did not want to present his own unconventional views without comment or explanation. However, in an important passage in the Commentary on the Epitome of De Caelo he discloses a little more of this thoughts:

Therefore Ptolemy assumed an epicycle ... and this is incompatible with what was established here [in the De caelo], as it was established

34 Commentary on the Epitome of the Meteorology, MS Berlin 110 ff. 113b col. b22-23, 114a col. a34-col. bl.

35 Commentary on Generation and Corruption, MS Vatican 342, f. 208a23. 36 Commentary on the Epitome of De Caelo, MS Paris 919, f. 200bIO-13; MS Ber-

lin 110, ff. 67b col. b30-68a col. al. 37E.g., Commentary on the Epitome of De Caelo, MS Paris 919, ff. 202al-3,

203a25-26, 212a3; Commentary on the Epitome of the Physics, MS Vatican 342 f. 3b22-23; Commentary on the Epitome of the Meteorology, MS Berlin 110, ff. 106a col. b15, 124b col. a30-32, 128b col. b22.



GERSONIDES' THE WARS OF THE LORD-GLASNER

here that this type of motion necessarily presupposes that there be something immobile at its center.... He also assumed a sphere eccentric to the center of the world, and this has been considered to be incompatible with what was established here [in the De caelo] concerning this motion that it is about something immobile, as other [scholars] have argued. But in our view it is not incompatible, at least according to what was established here, namely that the rotating body does not rotate about itself. Therefore, the rotating body must rotate about something. This something has to be either immobile or mobile. If it were mobile it should itself move about something different, and so on, until the process terminates with something immobile about which the motion is. This argument is valid also if the eccentric hypothesis is assumed. Generally speaking, if the motion in anomaly (qirn) is impossible unless caused by one or the other of these two alternatives [the epicyclic or the eccentric], then it is established that necessarily one of them holds. Indeed the true statement follows reality, not reality the true statement. Now it has already been established that one of them must be true, because there is no other way likely to bring about the observed motion in anomaly, except the moving poles, assumed by the master of new astronomy (nvtrn nitn 5ya) [al-Bitriiji], and we have already explained (ri)mx ii-na -ian) in the book of The Wars of the Lord that this astronomy falls short of accounting for what can be observed by the senses (vina nwzvv nn) concerning the apparent sizes of some planets, which are observed to vary from time to time. This [phenomenon] also makes it necessary to assume the existence of either an eccentric or of an epicycle. This [commentary] is, however, not the right place for this investigation, because the proofs from which follows the truth concerning this entire subject are mathematical. 38

In this passage Gersonides argues: (1) al-Bitr j''s attempt to avoid both the eccentric and the epicyclic models (postulated by Ptolemy) contradicts empirical evidence (viwrna mv nr). (2) Only Ptolemy's two models can explain the motion in anomaly of a planet. (3) There- fore, one of Ptolemy's two models must be true, contrary to the view of al-Bitr7ji. Gersonides follows the empirical principle: "because

38 The passage appears in all extant manuscripts of the Commentary on the Epit- ome of De Caelo: Berlin 110/2 (IMHM 1801), f. 68b cols. a8-b9; Paris B.N. 919 (IMHM 30913), ff. 201b5-202al; Paris B.N. 962/2 (IMHM 32610), f. 47b; Paris B.N. 963/2 (IMHM 32611), ff. 21 lb-212a; Roma, Cas. 132/1 (IMHM 106), f. 29b; Vatican 342/2 (IMHM 431), ff. 139b-140a; Jerusalem Mehlman 27/2 (IMHM 31545), f. 93a-b; Moscow Ginsburg 1594 (IMHM 48641), f. 134b.




the right statement follows reality, not that reality follows the right statement" (this is an important subject that will be discussed in section 11.2 below). (4) Aristotle's postulate that every rotation must be about an immobile body is compatible with the eccentric hypothesis, but not with the epicyclic (this will be explained in section 111.2). (5) The implied conclusion, not explicitly stated, is that the eccentric model is correct.

This argument indicates that at the time of the writing of the commentary (August-September 1321) Gersonides basically rejected al- Bitriiji's model, and tended to believe that the eccentric model was true, although he did not yet have conclusive empirical evidence, and was careful not to commit himself.

In the astronomical part of the Wars Gersonides states that he adopted the eccentric model, following an empirical re-examination of Ptolemy's two models. He even states that he developed his astronomical instruments for the purpose of re-examining Ptolemy's models. In chapter 46 he writes:

Therefore, wefirst tried to solve some of the difficulties raised against him [Ptolemy] by our predecessors [e.g., al-Bitriiji] with respect to his [Ptolemy's] postulates concerning eccentric spheres and epicycles, seek- ing to find observational evidence to establish his hypotheses (N?1n) 1NnTh 12 D)1 m V pn vIns). Indeed, the reason for which we invented the aforementioned instrument was to determine the amount of the eccentricity. 39

In chapter 9 he states that it was the question of the testing of the eccentric model that caused him to work on the improvement of measuring techniques:

You should know that we first invented this instrument to determine whether there is an eccentric sphere, for with it we can determine accurately the apparent size of the diameter of the moon at all four of its distances according to Ptolemy's model. The arguments of the physicists against Ptolemy's model brought this question to our attention. When we verified that this matter is not in accord with what Ptolemy assumed, we had to investigate models for the motions of the celestial bodies that would be in agreement with observation, and in particular with the variations in the observed distances. We shall use this instru-

" Wars V.1.46, P f. 88b7-10; Q f. 65b18-21 (translation from Goldstein, "A New Set," 385).




ment, to which God directed us, to find the truth in this science, as you will see.40

Gersonides also planned to measure the diameter of the sun (a task that required the technique of indirect observation provided by camera obscura) to learn if the sun's course is indeed eccentric.41 The measurements of the moon at different times of the month show that the differences in the moon's diameter are much smaller than those computed by Ptolemy following the epicyclic model.42 From the measurements of the sun Gersonides deduces "without the slightest doubt that the sun is fixed to a sphere eccentric to the center of the universe."43 In chapter 43 he refers to his own observations, which imply that Ptolemy's epicyclic models for the moon and Venus are invalid. In that chapter he presents in detail his arguments for rejecting the epicyclic model44 and for adopting the eccentric,45 and concludes: "It has been shown without any doubt that there is no other way to explain the observed motions of the planets, except by the eccentric hypothesis."46

These passages testify that Gersonides developed empirical methods (at least among other means) in order to decide between Ptolemy's two models, and to measure the eccentricity of the sun. In the Wars he used two values for the solar eccentricity, the earlier of the two being based on an observation made in 1334.47 The passage from the De caelo quoted above indicates that Gersonides tended to accept the eccentric model as early as 1321. This conclusion is strongly supported by the fact that by that time Gersonides was already working intensively on several aspects of the physical and cosmological "justification" of the eccentric model. (This subject will be discussed in detail in section III.) It is possible that over the years he became gradually more convinced, perhaps due to preliminary or

40 Wars V..9, G 264,55-58; English translation, G 72-73 (emphases mine). 41 Wars V.1.5, G 292, 18-20. The results of the observations of the moon: V.1.16,

G 240,1Off.; the results of the observations of the sun: V 1.19, G 231, 38ff. 42 Wars V.1.16, G 241,7-239,20. 43 Wars V1.19, G 231,38-40. 44 Wars V.1.43, Q 56bl9-59a26. 45 Wars V. 1.43, Q 59a27-60a8. 46 Wars V.1.43, Q 59a32-34. 47 See Goldstein, The Astronomical Tables, 93-94; J. L. Mancha, "The Latin Trans-

lation of Levi Ben Gerson's Astronomy" in Studies in Gersonides, 27.




experimental observations, but only many years later decided that the empirical evidence was fully satisfactory and conclusive.

11.2 Gersonides' Argument with al-Bitriiji: Reliance on Observation

Al-Bitriji's most grievous mistake was to neglect empirical evidence. Gersonides notes this problem already in his commentary on De caelo (see n. 38). In the Wars he writes that "both mathematical science (,nre'n 1rwn) and empirical evidence (v.rsn) conflict with this [al-Butrtiji's] model."48 Physical considerations led al-Bi riji to reject both eccentric and epicyclic models, but the agreement of his models with observation was much less satisfactory than that of Ptolemy's models.49

Al-Bitr-uji argues that "empirical evidence cannot be trusted, being misleading," and adds that "even Ptolemy himself admitted that theoretical conclusions should not be rejected on the basis of empirical evidence."50 Gersonides' reaction was to state his empirical principle: what was verified by observation cannot be denied by any theoretical argument. Gersonides was not the first to state this principle.51 It is significant, however, that he used this statement to make a point about how theory must conform to, and be based upon, observation. In this context and this sense the empirical principle was unusual. I have noticed in different contexts that when Gersonides repeats a principle several times such as his empirical principle, below, it indicates that this principle was of special importance to him:52

48 Wars V.1.44, Q 62a16. See also V.1.46, Q 65b13. 49 Goldstein, Al-Bitriuji, 6. 50 Wars V. 1.44, Q 63a3-5. 51 Aristotle states that "statements are true according to how the actual things are"

(De int. 9 19a32, Ackrill's translation: Aristotle's Categories and De Interpretatione [Oxford, 1963] 53), but the context-the truth value of certain type of sentences-is different. Maimonides quotes this principle, attributing it to Themistius: "That which exists does not conform to the various opinions, but rather the correct opinions conform to that which exists" (Guide 1.71; translation from S. Pines, 179). Maimonides quotes it as an argument against the Mutakallimuin, not as an empirical methodological principle. I thank the JQR reader for the reference to Aristotle.

52 compare the many citations of the principles "a rotating body rotates about something," and "the celestial body produces the up and the down" listed in sections 111.2 and 111.3 below.




We should not contradict empirical evidence [vnwns] because of the conclusions of our theoretical study Lwv], [based on] such weak premises, as Averroes and others did. This is because empirical evidence is the beginning of our theoretical study, not our theoretical study the beginning of sense data. Therefore, it is established that our theorizing should follow the empirical evidence [vniwn 1Tnh], and when we en- counter in it [the sense data] something that theory finds it hard to accept, we should not reject this sense data because of it, but should seek the causes for [the sense data] in a way that would not contradict the theory [w1v)].53

The existence of an eccentric sphere has already been established by the senses beyond any doubt, and such [theoretical] arguments are not strong enough to undermine what has been established beyond doubt by the senses. This is because true opinions follow reality, rather than reality following opinions that are considered to be true, and thus dictating our rejection of the evidence of the senses for them. 54

This principle is stated several more times in the fifth book of the Wars.55 As already noted it is stated as early as 1321 (see section 11.1 above).

Taking this principle seriously, Gersonides laid a very strong emphasis on accuracy, particularly the exactness of observations and the avoidance of errors. Thus he invented and improved astronomical instruments in order to achieve more accurate results;56 he mentioned several times that a slight error can lead to a larger error;57 he referred again and again to his attempt to be exact and to avoid errors;58 when describing his mathematical and mechanical tools he

5 Wars V.1.43, Q 59b36-60a3. 54 Wars V.1.42, P 75a29-34; Q 55a9-14. This sentence (as many others) illustrates

that the extant version of the argument against al-Bitr-uj-i was written (or updated) after the eccentric hypothesis was empirically verified to Gersonides' satisfaction.

55 Wars V.1.45, Q 63b34-36, 64b28-29; V.2.2, L 193. 561In Wars V.1.6-8 he describes the Jacob's staff, referring to it several times as

being "as accurate as possible" (V.1.6, G 281,1 and 278,48; V.1.7, G 278,1; V.1.8, G 268,1; V.1.17, G 238,3). In chapter V.1.12 he describes in detail how the common astrolabe should be improved in order to avoid errors, and what degree of accuracy can be achieved with it (V.1.12, G. 254,53). Chapter 15 describes how the position of the sun can be determined with the greatest accuracy using the method of the camera obscura (V.1.15, G 246,15 and 245,27).

57 Wars V.1.3, G 209,31 and 209,35; V.1.11, G 258,10-11; V.1.14, G 247,11; V.1.88, Q 125al4-15.

58E.g., Wars V.1.6, G 278,48; V.1.7, G 268,124; V.1.13, G 253,11.




often remarked that he could determine the degree of accuracy he de- sired;59 similarly, he often remarked with satisfaction that he achieved excellent accuracy (N5'o pnpi t? nv1p),60 and that his conclusions could be accepted without the slightest doubt. 61

This repeated emphasis on accuracy signifies that the notions of exactitude and of truth were almost synonymous for Gersonides. He said so explicitly, blaming his predecessors (notably Ptolemy) for being satisfied with approximations or close agreement (:nrp), and not doing enough to attain the truth (n ).62 The way to truth, for Gersonides, is a long process of approximation by repeated corrections and improvements.

11.3 Gersonides' Argument with al-Bitriiji: Reliance on Tradition

Al-Bitrflji's second apparent mistake was that he neglected Ptol- emy's system. Gersonides criticizes him severely for this adventurous approach and emphasizes the importance of relying on tradition.63

In this chapter we direct the community of scholars not to hasten to dissent from the views of the Ancients except after much investigation and careful scrutiny.... They should not hasten to dissent from the views of the Ancients, particularly when these views have been accepted by generation after generation of scholars over a long period of time. This is certainly the case in this science, for the community of investigators has followed the opinion of Ptolemy for about 1200 years. We have not found any trained scholar in this discipline who disputed his principles except for the author of the New Astronomy. 64

On the other hand, Ptolemy's theories are not satisfactory enough, and his observations are not reliable enough.65 Gersonides blames

59Referring to his trigonometric tables, V. 1.4, G 297-296,4; referring to his Jacob's staff, V.1.8, G 268,5; referring to the improved astrolabe V.1.12, G 254,53.

60E.g., V.1.3, G 298,47; V.1.8, G 268,1; V.1.13, G 254,1 and 253,10; V.1.15, G 247,15,21 and245,27; V.1.16,G241,7; V.1.55, Q79b29; V.1.79,Q 116al3;V.l.90, Q 134b34, 135a21.

61 E.g., Wars V.1.3, G 298,51; V.1.42, Q 55aIO. 62 Wars V.1.1, G 305,3. 63 Wars 60a27-28; V.1.45, Q 64b28-29; V.1.46, Q 65b9-15, 23-24; V.1.98, Q

142b20-21; in chapter 51 Gersonides sums up what has already been fully established by Ptolemy (V.1.51, Q 76b5-9); in chapter 55 he emphasizes the importance of com- paring his own observations with those of ancient astronomers, Q 79a31-33.

64 Wars V.1.46, Q 65b9-15 (Goldstein's translation, "Fourteenth Century Scien- tific Observations," 385).

65 V. 1.3, G 301,4-300,12.




Ptolemy for adjusting empirical data so that it would conform to his premises, and for neglecting observations that did not agree with his premises.66 Ignoring ancient observations is careless (as al-Bitrijil's attempt illustrates), but relying on them may be misleading:

What we have inherited from our predecessors has almost closed before us the door to finding the truth in this science.... What our predecessors did, removed us farther from attaining truth rather than bringing us nearer to finding the truth.67

Following his argument with al-Bitru-j1, we can see how Gerson- ides' particular understanding of the work of the astronomer evolved. Like his reliance on empirical evidence, so too reliance on tradition was essentially pragmatic and constructive. He highly esteemed Ptolemy, but took neither traditional parameters nor theories for granted. As already mentioned (section 11. 1 above), al-Bitrtiji failed because he hastily rejected both of Ptolemy's models. Gersonides carefully examines Ptolemy's theories and parameters (often by re- peating his observations), deciding what to accept and what to reject.

11.4 Gersonides' Argument with al-Bitriiji: Priority of the Mathematical Sciences

Both al-Bitrtiji and Gersonides were realists who tried to construct an astronomical theory compatible with natural science. Gersonides stated several times that "truth must agree with itself in all respects"

(X s ite iley vY zYn neznI).68 Yet, Gersonides' realism is significantly different from and more complex than al-Bitrtiji's. Al-Bitriujil took for granted the validity of Aristotelian natural science, and sought to construct an astronomical model consistent with natural science. Gersonides regards this approach as narrow and misleading: "This man did not follow the senses altogether, nor the mathematical sciences. He neglected these and devised his theory so that it would accord with the physical sciences only."69 Gersonides' own position was uncommon: the methods of mathematical astronomy are more

66Wars V.1.87, Q 124b22-37; V.1.46, Q 65b30-31; V.1.98, Q 142bl3-19; V.1.9, G 263,62.

67 Wars V.1.98, P 177b 21-28; Q 142bl2-19. 68 Wars V.1.16, G 239,24 (translation, G 103); V.1.28, Q 33a29; VI.1.15, L 358,

last line. The phrase is also found several times in the philosophical parts of the Wars. 69 Wars V.1.43, Q 55a21.




certain and reliable than the methods of the Aristotelian sciences. 70 As Kellner has shown, in the commentary on the Song of Songs (dated 1326) Gersonides places mathematics above physics and metaphysics in terms of verifiability.71

This reappraisal of the relationships between the sciences is based on Gersonides' deep faith in the validity of mathematics, and on his belief in the accuracy of observations achieved by the use of good instruments. I suggest that Gersonides, the natural philosopher, ven- tured to undertake the two difficult projects, and to try to answer the questions to which Maimonides had not given a decisive answer, because Gersonides was a mathematician and an astronomer. Gerson- ides' new conception of scientific certainty, based on mathematical and empirical knowledge, led him to believe that he had new tools with which to approach the old questions, and to succeed where others had failed.

11.5 Gersonides' Argument with al-Bitriiji: The Conception of Complexity

Gersonides criticized al-Bitriiji, as we have seen, for neglecting tradition and observation. He further criticized him for another, no less grievous, fault: neglecting the complexity of the phenomena. In chapter 42 Gersonides enumerates and refutes several apparent advantages of al-Bitrtiji's system. The first two are that al-Bitrtiji's planetary model satisfes two criteria: that nature does nothing in vain, and that nature does not accomplish with many devices (t) what can be achieved with few.72 Gersonides accepts both criteria, stating them himself several times,73 but shows that their fulfillment by no means implies simplicity (as does al-Bitrtiji's model).

Al-Bitrtiji's models were much simpler than Ptolemy's, and this was certainly a very attractive, yet false and misleading, feature. Ptolemy

70In his Treatise on Geometry he claims that he had attained a "demonstrative astronomy" (Carlesbach edition, 174).

71 M. Kellner, "Gersonides' Introduction to the Song of Songs" (Hebrew), Da'at 23 (1989) 22; "Gersonides on the Song of Songs and the Nature of Science," The Journal of Jewish Thought and Philosophy 4 (1994) 18-19.

72 Wars V.1.42, Q 54a26-29 and 54b2-5. 73Examples of references to the first principle: Wars V.1.27, Q 31b34; V.1.42, Q

54b4-5; V.1.44, Q 60b 16-17; V.1.97, Q 142a5. Examples of references to the second principle: V.1.52, Q 77b16-17.




introduced his complex models in order to get results "as close to the truth as possible according to his basic premises."74 In a fre- quently quoted passage, Ptolemy states that agreement with observation precedes simplicity: "One should try, as far as possible, to fit the simpler hypotheses to the heavenly motions, but if this does not succeed [one should apply hypotheses] that do fit."75 Al-Bitriiji, who "did not follow the senses altogether, nor the mathematical sciences" (n. 69 above), did not appreciate this consideration, and preferred to adjust astronomy to the simplicity and elegance of Aristotelian cosmology. The failure of al-Bitriiji's model leads to an important general conclusion: no simple astronomical model is possible. A model that accounts for the observed phenomena cannot be simpler than Ptolemy's, but, as Gersonides eventually concludes, has to be more complex.

Al-Bitriiji's model is much more economical than Ptolemy's: there is just one sphere that describes the daily motion, and its gradually reduced effect is transmitted to all other spheres;76 all celestial motions are in the same direction, from east to west, hence there is no problem of a cancelling effect, and of nature working in vain. No sphere is needed to account for the planet's motion in longitude from west to east, since this motion is understood as the reduction of the basic motion from east to west. To each planet is assigned one homocentric sphere, which describes the motion in anomaly by using the mechanism of rotating poles. 77

Gersonides easily dismisses the possibility that all movements are in the same direction and that the daily motion is gradually transmitted from one planet to another, but dwells much longer on the more weighty question of the correspondence between celestial movements and celestial spheres. In section 111.4, I shall discuss this subject further and show that it occupied Gersonides in the early period. Let me only mention here that Gersonides develops a "complex cosmology"

74 Wars V.1.46, Q 65b16-18. 75 Ptolemy, Almagest 13.2 (translated and annotated by G. J. Toomer [New York,

1984], p. 600). 76 In order to make this description possible al-Bitruji places Venus above the sun. 77 The planet rotates about an axis, while the north pole of this axis describes an

epicycle on the sphere, the center of the deferent being the north pole of the equator (chapter 4, explained with diagrams in Goldstein's introduction to Al-Bitrtuji: On the Principles of Astronomy 1:7-8). In the case of the sun an eccentric, rather than an epicycle, is projected on the sphere (chapter 9).




in chapter 27 of the astronomical part of the Wars, assigning a separate sphere to each celestial movement (rejecting not only the scheme of al-Bitriiji but also the cosmological schemes of Ptolemy and Averroes). Celestial movements can be explained only in terms of complex structures of eccentric spheres. Gersonides also accepts the equant model, which certainly adds further complexity to the system; he claims that this model completes the description of celestial motion, thus rendering the great variety of relations and actions in our sublunar world possible, and illustrating the utmost wisdom of God.78

Gersonides' understanding of complexity as an essential feature of nature is substantiated by his belief in natural astrology.79 Natural astrology "justifies" the great complexity of the celestial phenomena and shows that this complexity is constitutive and essential. Ger- sonides mentions twice that the purpose of spheres is for the stars; 80 and several times that the purpose of stars is for the stars' effect on the sublunar world.81 The eccentric model is especially well suited to explain the variety of celestial influences on the sublunar region because the varying distances of the planets account for the subtle effects that direct and ordain life on earth. 82 The following beauti- ful passage illustrates the deep association between Gersonides' astronomical project, his theory of creation, and his theory of natural astrology.

If these equal and opposite motions had no effect, this doubt [that they are in vain] would have been inevitable. But it has been established that they do have an effect, which cannot be otherwise accounted for- namely, the motion in anomaly (Iri5n) caused by this [multiplicity of movements]. If you study the acts of God, blessed be He, on His creatures, you will find that He does not abstain from inventing many devices in order to supply the creature with all the movements it needs. This is fully exemplified by the wonderful variety of devices (listed by Galen), which He has created in man (though man is just one creature) in order that all the movements that make man's being better and more

78 Wars V. 1.45, Q 65a2-5. 79 G. Freudenthal, "Levi ben Gershom as a Scientist: Physics, Astrology and Es-

chatology," Proceedings of the Tenth World Congress of Jewish Studies (1990) 65-72; Goldstein, "Astronomical and Astrological Themes," 222.

80 Wars V.1.44, Q 60b15; V.1.52, Q 77a35; V.2.1, L 191. 81 Wars V.1.52, Q 77b24. The subject is discussed in detail in V.2.3, L 194-197.

See also Gersonides' comment on Genesis 1:18 in Commentary on the Pentateuch, eds. B. Braner and E. Freiman (Jerusalem, 1993) 63.

82 Wars V.1.41, Q 54al3-15 and 54a29-b2; V.1.45, Q 64b32-36.




complete be accomplished. This [analogy] illustrates that it is not un- likely that He needed many devices (oi)5) in order to move the planet in such a way that makes possible its many effects on the sublunar world. 83

We do not know when this specific passage was written, but we know that both the theory of the multiplicity of eccentric spheres (section 111.4 below) and the theory of natural astrology were adopted in the early period. Gersonides dealt with the subject of natural astrology, and the effect of the particular astronomical models in his early commentaries.84 His discussion of celestial heat in the early version85 may also indicate that he was interested at that time in the subject of celestial influence.

I have tried to show that the Ptolemy/al-Bitriujl controversy played an important role in Gersonides' "scientific biography," and affected the formation of his methods and attitudes as an astronomer. It also influenced the first step in the evolution of Gersonides' astronomical project, namely, the acceptance of the eccentric model and the rejection of the epicyclic. The main argument for the early dating of this first step is the ample evidence that by 1321 Gersonides was already working intensively on the "justification" of the eccentric model. In theory, following Gersonides' own empirical principle, the step of physical "justification" should have come after that of empirical ver- ification (n. 54 above). In reality, however, the evolution of the astronomical project did not follow this "Baconian" scheme, but a more complex pattern.

III. THE FIRST STEPS OF THE ASTRONOMICAL PROJECT:

THE PHYSICAL AND COSMOLOGICAL "JUSTIFICATION"

OF THE ECCENTRIC MODEL

Gersonides developed a complex sophisticated argument to show that the eccentric model is physically possible. He drastically modified Aristotelian physics and cosmology, trying to adapt them to eccentric astronomy. This task of the "justification" of the eccentric model is actually the construction of Gersonides' own original cosmology. For the purpose of the adaptation of physics and cosmology to "eccentric astronomy," Gersonides introduced several physical and

83 Wars V. 1.37, P 69a28-b5. 84 Commentary on Generation and Corruption, MS Berlin 110, f. 97a, col. bh 1ff.;

MS Vatican 342, f. 208bl9ff. 85 See Appendix Commentary on the Meteorology, 1 and 6.




cosmological premises (nitprn) in different chapters of the astronomical section of the Wars. These premises, though mostly taken from Aristotle or Averroes, were reinterpreted by Gersonides, and eventually resulted in a cosmology that differs considerably from the Aristotelian.

Gersonides' "eccentric cosmology" includes several major theses: (1) a new explanation of the mechanism of rotation; (2) a new explanation of the linear motion of the four sublunar elements; (3) the thesis that a separate sphere corresponds to each celestial movement; (4) the thesis that within the spheres of each planet, motion is transmitted from the innermost to the outermost; (5) the thesis that the spheres of different planets are separated by a body that does not preserve its shape.

I shall present the physical and cosmological premises introduced in Book V.1, and the theses developed on the basis of these premises, and I shall try to show that they were introduced in order to adapt Aristotelian science to the eccentric model.

The first two arguments are developed in chapter 43 of the astronomical part of the Wars, and are also presented in the commentaries on Averroes. The commentaries explicitly refer several times to the argument in the Wars. Hence these two theses were a part of the early version of the Wars. 86 The three latter arguments are presented mainly in the group of chapters 26-31. The third thesis is also alluded to in the commentaries, with an explicit reference to the Wars, and therefore was probably also included in the early version. Of the fourth and fifth, I found no early evidence. I shall argue in section 111.6 that the fifth thesis was indeed introduced later. It is interesting to note that these major theses of Gersonides' "eccentric cosmology" are presented in the technical astronomical part (V.1 of the extant edition of the Wars), which is addressed to astronomers, rather than in the cosmological part (V.2). This arrangement shows to what extent Gersonides' cosmology was "astronomically oriented."

111. 1 Other Physical Premises Introduced in the Astronomical Part of the Wars

In order to give a complete account of the physical and cosmological premises in the astronomical part of the Wars, I shall mention

86 This does not mean, of course, that chapter 43 in its present form was a part of the early version.




briefly the two premises introduced in chapter 20 of the astronomical part of the Wars:

Before this we must mention two principles (oi'viv) that are needed for this investigation. The first principle is that the stars [and planets] are affixed to spheres and that they move with the motion of these spheres, the part moving with the whole. The second principle is that the motion of the celestial bodies is necessarily uniform in itself, and that the apparent variation is related to the way we see it, not that the motion itself varies.87

As to the first premise-that the stars are fixed to the spheres- Goldstein has shown that Gersonides needed it in order to refute the epicyclic model. Assuming Gersonides' principles, the epicyclic model is inconsistent with the empirical fact that we always see the same side of the moon, while the eccentric model is consistent with this observed fact. 88 The second premise-that planetary motion is uniform in itself, but not necessarily with respect to the observer (who is not at the center)-is also a "justification" of the eccentric model.

111.2 The Premise that a Rotating Body Rotates about Something

Aristotle argues in De caelo that the structure of the heavens and the mechanism of circular motion imply that there must be an immobile body (the earth) at the center of the universe:

Because there must be something at rest at the center of the revolving body, and of that body (the fifth element) no part can be at rest, either elsewhere or at the center. . . . Earth then has to exist, for it is earth which is at rest at the center. 89

This conception is emphasized by Maimonides:

It is one of the preliminary assumptions of Aristotle in natural science that there must necessarily be some immobile thing around which

87 Wars V.1.20, G 230,3-6 (Goldstein's translation, 114). 88 Goldstein, "Theory and Observation in Medieval Astronomy," Isis 63 (1972) 41-

42 (reprinted in Goldstein, Theory and Observation; The Astronomical Tables of Levi ben Gerson, 24-26).

89Aristotle, De caelo 11.3 286al 1-14, 20 (J. L. Stocks' translation in the Oxford edition). Gersonides was familiar with Aristotle's thesis through the Hebrew translation of Averroes' Middle Commentary on De Caelo, ma'amar 2, kelal 2, mevuqash 2. I have consulted Shlomo Ibn Ayub's translation, MS Berlin 212 (MS Or. Qu. 811), IMHM 1769, f. 43a. Aristotle also proves, from a consideration of the natural motion of the earth, that the center of the whole and that of the earth coincide (De caelo 11.14 296b6-21; see also Phys. VIII.9 265b2-8).




circular motion takes place. Hence it is necessary that the earth should be immobile. 90

In order to adjust natural science to eccentric astronomy, Gerson- ides had to reinterpret Aristotle's statement that in the center of every circular motion there must be a body at rest. For this purpose he invoked the premise that "a body in motion moves about something different from itself." This premise is mentioned already in three of the early commentaries91 and at least four times in the astronomical part of the Wars.

It has been established in the Physics that, of necessity, everything that rotates has something in the middle about which it rotates.92

It is false that it moves about itself, for a moving body, qua moving requires something about which the motion takes place. It is therefore clear, as this has been specified in the natural science, that something cannot move about itself.93

Because the moving [body] does not move about itself, it is established that there exists necessarily something about which the motion takes place.94

The Philosopher has already posited, concerning this matter, that it is self-evident that a moving [body] does not move about itself; therefore, it should move about something else.95

Gersonides ascribed this principle to Aristotle, but in fact he referred to a passage from Averroes' middle commentary on the Physics: 96

90 Maimonides, The Guide of the Perplexed 2.24, Pines, 323. 91 Commentary on the Epitome of De Caelo, MS Paris 919, f. 201bl5-16; Com-

mentary on the Epitome of the Physics, MS Berlin 110, f. 16a, col. a27-28; 16b, col. b3-4; Commentary on the Middle Commentary on the Physics, MS Paris 964, f. 66b 18-19, 22-23.

92 Wars V.1.29, Q 33b18-19. 93 Wars V.1.43, Q 57al2-14 (Freudenthal's translation). 94 Wars V 1.51, Q 77aI2. 95 Wars V. 1.43, Q 59b 13 -14. 96 Averroes also mentions this principle in the Long Commentary on De Caelo, but

this commentary was not known to Gersonides. Concerning this reference and its meaning, see H. Hugonnard-Roche, "L'6pitom6 du De caelo d'Aristote par Averroes: questions de methode et de doctrine," Archives d'histoire doctrinale et litteraire du moyen age 51 (1984) 36-37.




The sphere, by nature and by its being spherical, needs an image (n1rnn)97 and a convex immobile body about which to rotate. This is called "center." This has been established by Aristotle in the De caelo, namely, that circular motion is impossible unless there be an immobile body about which it rotates. This is the center, which is the place of the moving body in this motion. This is why it [the center] is immobile, as it was established that place is essentially immobile. Furthermore, the center is necessarily separate from the sphere, i.e., it is not a part of it [the sphere].98 And what is separate is necessarily a body, since what is indivisible cannot be separated. And as every sphere has a separate immobile center (this being the property of place), the convex surface of the center is the inner boundary of the sphere. 99

In this passage Averroes indeed ascribes to Aristotle the view that rotation is necessarily about something. According to Averroes' interpretation: (1) in the case of a rotating sphere this "something" is the center of the sphere; (2) the center is separate (>Xt3) from the sphere; (3) the center is the (immobile) place of the rotating body, its convex surface being the inner boundary of the sphere.

In order to prove that the center is separate from the rotating body, Averroes offers a "mathematical demonstration": given a circle rotating about the center, each point on a radius describes a circle. This, according to Averroes, applies also to the center point itself. The circle (n)>v), described by the center, cannot be a vacuum (because there is no vacuum), hence it is a body. This circular body must be immobile, otherwise the argument will lead to an infinite re- gression. It cannot be just a point, because a point can be in motion or at rest only accidentally.'l0 This "proof," applied to the three- dimensional case, implies that the center is separate from the sphere, its convex surface being the inner boundary, and hence the place of the solid sphere.

97 The text is not clear. Perhaps the allusion is to the image of the celestial mover that causes the sphere to move; for our purposes, the relevant part of the sentence is the second.

98 The MSS differ in this sentence. I followed Oxford Bod. 1380 and 1381. 99 Averroes, Middle Commentary on Physics, ma'amar 4, kelal 1, chapter 9, MS

Paris 941 (IMHM 30918) ff. 53b21-54a8. I consulted three more manuscripts: Wien Nationalbibliothek MS Hebr. 154 (IMHM 1328); Oxford Bod. 1380/1 (IMHM 22404) and 1381/1 (IMHM 22405).

l0 Ibid., MS Paris 941, f. 54a9-24.




Gersonides accepts the premise ascribed by Averroes to Aristotle, namely that rotation is about an immobile body, 101 but rejects Aver- roes' interpretation. Using a simple geometrical argument, he refutes Averroes' "mathematical demonstration" that the center is separate and can be regarded as the immobile body about which the sphere rotates.102 Gersonides' own view is that rotation must be about a "really different" body. 103

The same argument appears three more times. In a long discussion in the Commentary on the Epitome of the Physics, Gersonides says that the rotation of a sphere cannot be rolling or rotating about the concave surface of an encompassing body. It must be about another immobile body at the center. 104 In the Commentary on the Epitome on De Caelo he states explicitly that rotation is about a different body, and emphasizes that the eccentric hypothesis is not incompatible with this model of rotation (n. 38 above).

The significance of the subject becomes clear in the Wars. 105

Gersonides explains that Averroes' argument (which he takes to be Aristotle's) actually implies less than Averroes contends. Averroes contends: (1) it is evident that a rotating body does not rotate around itself but around something different; (2) this "something" about which it rotates is encompassed, not encompassing; and (3) the process necessarily terminates with an immobile body at the center. Averroes' conclusion is that every celestial body rotates about the earth, which is in the center. Gersonides' analysis yields weaker conclusions: (1) each sphere indeed rotates about the convex surface of a body encompassed by it, but not necessarily about the center of the earth; (2) only the last moving body in the chain must rotate about the earth; and (3) therefore only the last moving body must rotate about the center of the world. According to Gersonides' interpretation Averroes' argument does not contradict the eccentric model. Only the innermost sphere of the moon rotates about the earth, while the other

101 Gersonides, Commentary on the Middle Commentary on De Caelo, MS Parma, Palatina R. 805 (IMHM 13659), f. 29bl-2; Commentary on the Epitome of De Caelo, MS Paris 919, f. 201b8-9.

102 Commentary on the Middle Commentary on the Physics, MS Paris 964, f. 66a2 1- b14.

103 Ibid., f. 66bl4-19. 104 Gersonides, Commentary on the Epitome of the Physics, MS Berlin 110/1, ff. 16a

col. a27-16b col. a26. 105 Wars V.1.43, Q 59b11-31.




spheres rotate about something immobile encompassed by them. This argument will be made clear in section 111.6.

111.3 The Premises that the Rotating Body Produces "the Up" and "the Down," and that "Heavy" and "Light" are Relative Concepts

In chapter 43 of the astronomical part of the Wars, Gersonides ex- amined the arguments against the eccentric and the epicyclic models, following al-BitrtijI's rejection of these models. We have seen that in this chapter he explained in detail the premise that "every rotating body rotates about something" and its compatibility with the eccentric hypothesis (notes 92-95 above). In the same chapter he also introduced two additional premises (nrrpn), which are relevant to the adaptation of natural science to eccentric astronomy:

For the sake of the explanation, we first put forward two premises. The first is that it is the celestial body that produces the up and the down. This premise has already been established in natural science. The second [premise] is that the motion of the elements results from their being light or heavy in relation to one another. 106

The statement that "the up" and "the down" are produced by the rotating celestial body is taken from Averroes, 107 who follows Avi- cenna.108 Gersonides repeats and emphasizes this principle many times. It appears five times in the two commentaries on De caelo, 109 four times in chapter 43 of the astronomical part of the Wars, 110 and again in the sixth book.111 I have dealt with this subject separately and have shown that on the basis of the two premises introduced in chapter 43 Gersonides constructs his non-Aristotelian theory of natural motion, which does not presuppose the existence of natural

106 Wars V. 1.43, Q 56a3-5 (Freudenthal's translation). 107 Averroes, Middle Commentary on De Caelo, MS Berlin 212, f. 22,16; Epitome

of De Caelo, MS Paris h6b. 918 (IMHM 31960) f. 56a col. b19-22. 108lbn Sind, Al Najah (Cairo, 1912) 211-217; Livre des directives et remarques,

translated by A. M. Goichon (Beirut, 1951) 279-282. See also S. H. Nasr, An Intro- duction to Islamic Cosmological Doctrines (Boulder, 1964) 223-224.

109 Gersonides, Commentary on the Epitome of De Caelo, MS Paris 919, ff. 173a25- 173b3 and 173bl8-19; Commentary on the Middle Commentary on De Caelo, MS Parma 805, ff. 30al8-20, 31a7-9, and 32a24-32bl.

110 Wars V.1.43, P 55b9, 55b12, 56a35-36, 57a20. ' Wars VI.1.18, L 376-377.




places and explains the motion of a body in terms of its relations to adjacent bodies in contact with it.112 The body rises when the medium surrounding it is heavier and sinks if it is lighter.

The statement that "the rotating body produces 'the up' and 'the down"' is a physical statement. The distance from the celestial body determines the degree of heaviness or lightness of the sublunar medium. The resulting structure of the medium, rather than natural places, determines the natural motions of bodies in the sublunar region. In this system there are no absolute "up" and "down," and the center is the natural place of the earth only accidentally. 113 The "up" and "down" do not determine the structure of the cosmos, but are themselves determined by the last moving sphere, namely, the innermost lunar sphere. We shall see in section 111.5 that according to Gersonides, the innermost lunar sphere describes the daily motion.

111.4 The Premises Related to the Correspondence between Movements and Spheres, and to the Transmission of Celestial Motion

In the Guide (2.4) Maimonides refers to the question of the correspondence between celestial movements and spheres. He mentions two explanations found in Aristotle and contemporary philosophers. Aristotle assigns a sphere to each motion, but this model is outdated "for in his time there was little knowledge of mathematics, and this science had not been brought to perfection. It accordingly was thought that every motion requires a separate sphere. For they did not know that many apparent movements may result from the inclination of one sphere." 114

Gersonides (Wars V.1.27) discusses in detail the two explanations mentioned by Maimonides (and also a third, al-Bitriiji's). He questions "whether it is possible that there be a multiplicity of movements,

112R. Glasner, "Gersonides' Theory of Natural Motion," Early Science and Medi- cine 1 (1996) 190-195. Gersonides' theory of natural motion is never presented sys- tematically; the closest he comes to a systematic presentation appears in Wars V.1.43. Many passages and sentences in the commentaries confirm the presentation found there. Commenting on Averroes, Gersonides has to use the term "natural place" in the Aristotelian sense, yet his different interpretation of natural motion is mostly consistent throughout his writings.

113 Wars V.1.43, Q 56a25-27. 114 Guide 2.4 (Pines, 257). That the science of astronomy was not completed in

Aristotle's time Maimonides states also in 2.19 (Pines, 308) and 2.24 (Pines, 326).




without assuming a multiplicity of spheres, as some of the early scholars assumed," 115 and lists three answers, which correspond to three cosmological schemes.116

The first was the scheme of Aristotle-to each celestial motion corresponds a sphere. This scheme, based on the models of Eudoxus and the modifications of Callipus,117 was not clearly understood by the Arabs. Averroes comments that "when people came to think that these [Ptolemy's] astronomical models made it simpler and easier to explain the recurrence of the motions, they abandoned the old astronomy, so the knowledge of it passed away and today one cannot understand what Aristotle says in this passage." 118 Maimonides rejects Aristotle's scheme as outdated (n. 114 above). In Aristotle's system there were 55 or 47 spheres. 119

According to the second scheme of the Arab Aristotelians, the number of spheres is less than the number of motions. This system is based on the synthesis suggested by Ptolemy in his Planetary Hypotheses. Maimonides ascribes it to contemporary scholars; Ger- sonides, to Ptolemy and Averroes. This system assigns to each planet a sphere, which encompasses the eccentric and epicyclic orbs that describe the motion of the planet. The term "sphere" was often used ambiguously in both senses. In order to avoid confusion I shall use "orb" for each eccentric or epicyclic component, and "sphere" for the set of orbs that refer to a single planet. Altogether there are nine or ten spheres. 120 The concept of sphere helped Arab Aristotelians "hide" the problematic eccentric and epicyclic orbs between two homocentric boundaries. Further, it accorded better with al-FarTbi's and Avicenna's scheme of emanation. A system of nine or ten separate intellects was more compact and elegant than a system of about fifty.

The third system referred to by Gersonides is that of al-Bitru-jI. In this system only one orb corresponds to each planet. The movements common to all planets-namely, the daily motion and the motion of

115V.1.27, Q 30al8-19. 116 Wars V.1.27, Q 30a22-27. Gersonides' analysis in V.1.27 is discussed in more

detail in my "Gersonides on Simple and Composite Movements," Studies in the His- tory and Philosophy of Science 27 (1996).

117 Aristotle, Met. 1073b28-1074al5. 118 Averroes, Long Commentary on the Metaphysics, ed. Bouyges (Beirut, 1948)

1663; translation taken from C. Genequand, Ibn Rushd's Metaphysics (Leiden, 1984) 178-179.

119 Aristotle, Met. 12.8 1073b36-1074al3. 120 Depending on whether trepidation was assumed.




precession-are transmitted to all the planets, their influence being gradually reduced. The motion in longitude from west to east is thus explained. The only motion specific to each planet is the motion in anomaly, so to each planet just one orb is assigned. 121

After posing the question at the beginning of V.1.27, 122 whether a multiplicity of movements implies a multiplicity of orbs, Gerson- ides asks "whether the orbs are moved by each other or not." 123 The two questions are related, since the different systems (listed above) dictate different conceptions of transmission.

In Aristotle's system the orbs move each other mechanically. The outermost orb of each planet describes the daily motion from east to west; the second describes the longitudinal motion of the planet from west to east along the ecliptic. 124 The function of the other orbs of the planet, in the Eudoxus-Callipus system, was not altogether clear to the Arabs. It was usually assumed that the third describes the lat- itudinal motion-namely, the deviation of the planet from the ecliptic. 125 Following this scheme transmission was easily explained. The poles of each of the orbs of a planet are attached to the orb encompassing it, so motion is mechanically transmitted, the planet being attached to the innermost of its orbs. Gersonides refers to this model as transmission by contact (w1w)o 126 or PI-Inn 127).

In the system of the Arab Aristotelians the subject of the transmission of motion if problematic. There is one sphere for the daily motion, one for precession,128 and the seven spheres of the seven planets describe the specific motions (in longitude and in anomaly) of the corresponding planets. There is no "multiplication," no "daily motion orbs" within the spheres of the planets. This structure actually rules out the explanation of transmission by contact between adjacent orbs. Gersonides quotes a passage from Ptolemy's Planetary Hypotheses in which Ptolemy admits: "we cannot think of a mechanical device (n5ann) [which can account for] the power [by means of

121 See section 11.5 above.

122V.1.27, Q 30al8-19. 123 V 1.27, Q 30a29-30. 124 The motion of precession was not yet known to Aristotle. 125 E.g., Averroes, Long Commentary on the Metaphysics, Book lam, 1667-1668

(on Met. 1073b22-3 1), Genequand's translation, 180-18 1. 126 Wars V.1.27, Q 32b18, 33a18,21. 127 Wars V.1.27, Q 30b21, quoting Ptolemy. 128 Those who believed in the theory of trepidation added another globe.




which] the first sphere [in a series of spheres] in contact with each other, moves all the other spheres." 129 Consequently Ptolemy employs an organic metaphor:

What is perceived of flying creatures is taken as a metaphor (~)v3) for the movement of what is in the heaven.... The movement of the flying creature originates in its "conducting power ()-n3wn nzn)" which produces the emanated power (n'vrn nzn), and this is transmitted to the nerves and from the nerves to the hands, feet, and wings, where it terminates.... Nothing implies that the movements of the flying creature, all of them or part of them, are [transmitted] by contact from part to part. It cannot be by contact, if we do not allow that parts be moved by other parts. The same should apply to the animate sphere. 130

Averroes briefly mentions the living creature metaphor in his middle commentary on De caelo,131 and explains it in detail in his Epitome of this text:

We say that it is apparent that this body [the heavens] is one body, as it moves this one single motion, and the rest of the movements in it are partial movements, with respect to this motion. This is so because it is an ensouled being, like a living creature, having its general local motion (nrf nvyin) and the partial movements of its limbs. 132

Gersonides ascribes to Averroes the view that the motion of the whole is caused by the soul of the organism and the specific movements are compared to the movements of the limbs. According to Gersonides' terminology, transmission in Aristotle's system is by contact (vwm) while in the system of Averroes the motion that originates in the soul propagates (nuvnnz) in the different spheres. 133

Maimonides uses a similar metaphor: "so is this whole being one individual that lives in virtue of the movement of the heaven."'134

129 Wars V.1.27, Q 30b20-21. 30 Ibid., 30b26-32.

131 Averroes, Middle Commentary on De Caelo, book 2, kelal 3, mevuqash 5, MS Berlin 212/2 (IMHM 1769) f. 52a8-15.

132Averroes, Epitome of De Caelo, MS Paris 918/3 (IMHM 31960) ff. 54b-68b, on f. 64b col. b 9ff.

133 Wars V.1.27, Q 30b9-12. In simple organisms, cut off limbs keep moving for a while. This applies to animals like frogs, and to the young shoots of certain plants, and also to the spheres, which are perfectly simple (ibid., 30b13-165).

134 Guide 1.72 (Pines, 187); see also 1.72 (p. 184) and 2.10 (p. 270).




Maimonides also employs the model of propagation: "the other parts of the body are ruled by the heart, which in virtue of its motion sends toward them the forces they require for their functions; so heaven in virtue of its motion exerts governance over the other parts of the world and sends to every generated thing the forces that subsist in the latter. 135

Gersonides does not follow his three great teachers. He provides a long refutation of the scheme of the Arab Aristotelians (which applies also to the system of al-Bitriiji) and of the organic account of transmission,136 and adopts a new, more sophisticated and updated version of the system of Aristotle. For the sake of this important argument he introduces three premises. 137 The first two state that numerically one body has numerically one form, and that numerically one body has just one self-motion. 138 The third premise actually lim- its the possible relations between a whole and its parts allowing three alternatives: either the form is present in each part after a body is actually divided (as in homeomeres and some plants), or in some of the parts (as in a living animal), or in no part (as in a dead animal). Re- lying on these premises Gersonides argues in detail that the form that causes the motion of the whole can be neither one for each sphere separately nor one for all. 139 The argument clearly intends to exclude vague or obscure accounts of transmission. In the scheme of Aristo- tle, the complexity of celestial motion is fully explained in terms of direct transmission, no "remote control" being necessary.

Gersonides follows Aristotle in including orbs that describe the daily (and precession) movements within the spheres of each planet, in the mechanical account of transmission, and in separating the movements of the different planets. 140 His system is much more complex than Aristotle's as the orbs are eccentric; however, it admits no epicycles, which require a more complex pattern of transmission.

13 Guide 1.72 (pp. 186-187). 136 Wars V.1.27, Q 31a26-b37. 137 Wars V.1.27, Q 31al2-24. 138 This Aristotelian principle is also invoked by al-Bitrtiji, On the Principles of

Astronomy 1:24. 139 Wars V.1.27, Q 31a28-b37. 140 Aristotle accounts for this separation by the hypothesis of the unrolling spheres;

Gersonides by the hypothesis of the body which does not preserve its shape (section 111.6 below).




The analysis in V.1.27 is, therefore, a major step in the development of Gersonides"'eccentric cosmology." There is evidence (though scant) that this analysis was included in the early version of the Wars. It is briefly alluded to in the Commentary on the Epitome of De Caelo (see below, Appendix, pp. 44-45, 6). The passage appears in all extant manuscripts of this commentary.141 Commenting on the statement that "all spheres participate in one motion," 142 Gersonides adds that such an account raises doubts. If indeed the daily motion in the spheres is to be explained in this way, namely mnt'5n n, it should imply that as in the case of the living creature-who, when moving its arm moves also its hand in the same motion-so also the specific motion of one planet must necessarily be transmitted to another. Such an account necessitates a mechanism of counteracting movements and involves much redundancy. He adds: "And we have already elabo- rated on this (ta 1n n inir) in the book The Wars of the Lord." 143 This passage questions Averroes' thesis that "all spheres participate in one motion," most likely referring to the discussion on the transmission of celestial movements in V.1.27 and 28.

One of Averroes' arguments for regarding the heavens as a living creature is that in the heavens there is a natural distinction between left and right, and such a distinction is typical of living creatures, not of inanimate bodies. 144 Gersonides rejects the thesis that there is a natural distinction between left and right in the heavens. This rejection is found in the commentaries, with references to the (early version of ) the Wars. 145 This attitude also reflects Gersonides' conception of celestial movements, which is more mechanistic than that of the Arab Aristotelians. The rejection of the organic models of transmission and the construction of a more mechanistic cosmological scheme, along the lines of the forgotten Aristotelian scheme, were included in the early version of the Wars.

141MS Berlin 110 ff. 75b-76a; MS Paris 919, f. 213a; MS 962, f. 52b; MS 963, f. 227a; MS Roma 132, ff. 38b-39a; MS Vatican 342, f. 156b; MS Jerusalem Mehlman 27, f. lOOa-b; MS Moscow Ginsburg 1594, ff. 144b-145a.

142Averroes, Epitome of De Caelo, MS Paris 918/3 f. 65a col. a13. 143 See Appendix, Commentary on the Epitome of De Caelo, 6. 144 Aristotle, De Caelo 11.2, 284b31-32; Averroes, Epitome of De Caelo, MS Paris

918/3, f. 61a col. b21-23. Middle Commentary on De Caelo, MS Berlin 212, f. 41b15-18.

145 See Appendix, Commentary on the Epitome of De Caelo, 3, Commentary on the Meteorology, 5.




111.5 The Argument that the Transmission of Motion within the Sphere of Each Planet is from the Innermost Orb to the Outermost

In a cosmological model, based on Gersonides' new interpretation of rotation, all celestial orbs, except the innermost orb of the moon, can be eccentric. The inner orb of the moon, however, must rotate about the earth (section 111.2 above). In chapters 28 and 29 of the astronomical part of the Wars, Gersonides introduces an original thesis: within the sphere of each planet the transmission of motion is from the innermost orb to the outermost, and not the other way around. 146 The planet is attached to the outermost of its orbs, rather than to the innermost, as was commonly taken for granted since Eu- doxus. 147 According to this thesis the innermost lunar orb describes the daily rotation from east to west and its center indeed coincides with the center of the earth. This thesis is obviously an essential part of Gersonides' "eccentric cosmology." It is also substantiated by empirical evidence. Comets and other meteorological phenomena that belong to the upper region of fire are influenced by the daily motion, but not by the specific movement of the moon. 148

I did not find references in the commentaries on Averroes to the thesis that motion is transmitted from the innermost orb of each planet to the outermost. A rather obscure passage in the commentary on Job (from the end of 1325) may allude to this thesis, but this is far from clear. Gersonides comments on Elifaz' words wni -mrn MIs )_ ' ("See the height of the stars, how lofty"). 149 The argument is found both in the explanation of the words and in the general explanation of the text. Gersonides suggests two possible interpre- tations. According to the second "'the height of the stars' is the name of the place where the planets are always in their mean motion, 150 as this place is of the utmost height and elevation, as we have explained

146B. R. Goldstein, "Preliminary Remarks on Levi ben Gerson's Cosmology," Creation and the End of Days, ed. D. Novak and N. Samuelson (Lanham MD, 1986) 265-269.

147 Wars V.1.29, P 34a22-23. 148 Wars V. 1.29, P 33b34-34a22. 149 Job 22:12.

150 The text reads oin nn.zr). I assume that it should be on)il onn)On.




in the book The Wars of the Lord." 151 According to the second version, "he may mean by 'the height of the stars' the height of the orb which describes the planets' motion in longitude, where the planet always is, due to its motion in longitude always. 'How lofty'-as I have explained in the fifth book of The Wars of the Lord." 152

According to these two passages the place that is "of the utmost height" (for each planet) is the place of the orb that describes the motion of the planet in longitude (variations in distance, due to the motion in anomaly are ignored). This seems to imply that the orb that describes the motion in longitude is higher than the other orbs (which describe the daily motion and the motion of precession). If this interpretation is correct, the reference to the Wars is to chapter 29, and we can date the theory of transmission from the innermost to the outermost orb before the end of 1325.

The four physical premises that Gersonides adopts-that a rotating body rotates about a body different from itself, that "the up" and "the down" are produced by the rotating celestial body, that "heaviness" and "lightness" are relative, and that the innermost orb of each planet describes the daily rotation-all imply that the center of the world is of no special physical or cosmological significance. It is neither the immobile body about which the spheres rotate, nor the absolute "down" toward which the heavy elements move. It is actually produced by the rotation of the innermost lunar orb. Gersonides' "eccentric cosmology," however, is still incomplete without the hypothesis of the body that does not preserve its shape.

111.6 The Hypothesis of the Body that Does Not Preserve Its Shape between the Spheres of Different Planets153

The hypothesis of the body that does not preserve its shape is introduced in chapter 28 of the astronomical part of the Wars and is

151 Commentary on Job (Ferrara, 1477) f. 59b; Miqra'ot Gedolot 5:17la-b; English edition (not used): A. Lassen, The Commentary of Levi ben Gersom on the Book of Job (New York, 1946) 141.

152 Commmentary on Job (Ferrara) f. 61a, Miqra'ot Gedolot 5: 172a. 153 Concerning the meaning of the term and the nature of this body see G. Freu-

denthal, "Cosmologie et physique chez Gersonide," REJ 145 (1986) 295-302; J. J. Staub, The Creation of the World according to Gersonides (Chico CA, 1982) 5, n. 49 and pp. 185-206; Touati, La pensee philosophique, 249-254.




referred to in several other chapters (V.1.37, 97, 130-131). It is discussed in detail in the cosmological part of the Wars (V.2.2). It is referred to several times in the context of Gersonides' theory of creation (VI. 1.17, VI.2.7) and in the commentary on the Pentateuch.154 These texts are dated November 1328 to October 1329.

The hypothesis of the body that does not preserve its shape is essential for "eccentric cosmology" in more than one way. First, it explains why the movements of the different planets do not interfere with each other. This is the context in which the concept is first introduced. Gersonides comments: "Already our predecessors were occupied by these doubts, and therefore they assumed (according to my understanding) another body among the orbs of one planet and the orbs of the other planet." 155 The hypothesis of the body that does not preserve its shape provides the missing link in Gersonides' thesis of mechanical transmission of celestial motion (section 111.4 above), 156 and eventually leads to Gersonides' original theory of cosmic distances.

Second, it solves the problem of the contact between an eccentric orb and the orbs above or below it (assuming the impossibility of a vacuum). Maimonides and al-Bitrtiji noticed this problem. Al-Bitr-ujjl comments that "[the sphere] must either be moved or carried along with its parts when the eccentric and epicyclic spheres in it move, implying that the encompassing sphere for these spheres would have to be like air or water and flow with its parts." 157 Maimonides comments that, because a vacuum cannot exist in nature, "necessity obliges the belief that between every two spheres there are bodies other than those of the spheres." 158 In V. 1.97 Gersonides remarks that this problem is an additional consideration that compels him to assume the existence of a body that does not preserve its shape. 159 In chapter 130 he explains this notion in detail:

154 Gersonides, Commentary on the Pentateuch, vol. 1, Genesis, ed. B. Braner and E. Freyman (Jerusalem, 1993) 34, 45, 46, 48, and 50.

155Wars V.1.28, P 46b4-6; Q 33alO-12. Gersonides adds that Maimonides had mentioned this at the end of the first part of the Guide. He does not refer to Mai- monides statement in 2.24 (quoted below), but to his discussion of the Mutakallimiun's refutation of corporeality in 1.76. In this discussion the celestial body is mentioned several times, but not explicitly the interstellar body.

156 Wars V. 1.28, Q 33a22ff. 157 Al-Bitrflji, On the Principles of Astronomy 2:40-42 (Goldstein's translation 1:60). 158 Maimonides, Guide 2.24 (Pines, 324). 159 Wars V. 1.97, Q 142a30-37.




The thickness of the thicker side [of the spherical shell] may be greater than the thickness of the side opposite it by the sum of twice the eccentricity of the sphere of apogee and twice the eccentricity of the sphere of the mean motion. But when the apogee of the convexity of the sphere of the mean motion is in the direction of the perigee of the convexity of the sphere of the apogee, there will be a diminution in the excess of thickness that we mentioned by double the eccentricity of the sphere of the apogee, twice, and the shape of the fluid differs in this place from the first shape varying in this way and producing innumerably many different shapes. It also follows that some of the fluid moves because of the motion of the sphere of the planet below it. From this it is also clear and without doubt, that of necessity the fluid lies between the spheres of one planet and those of another in such a way that it is compelled to receive these different shapes. 160

Third, it solves the problem of the center of motion. As explained in section 111.2, Gersonides agrees with Aristotle and Averroes that a rotating body rotates about something, but according to his interpretation only the innermost orb of the moon must rotate about the earth. All the other orbs, according to Gersonides, rotate around the body that does not preserve its shape. This body has no motion of its own, 161 and the thickness of its layers is computed such that at the center of each layer the movements of the spheres below and above no longer have any effect. 162 Consequently rotation is indeed about an immobile body. 163

The hypothesis of the body that does not preserve its shape is, therefore, essential for Gersonides' astronomical project. With this hypothesis the physical justification of the eccentric model is completed. Gersonides' cosmology is fully compatible with eccentric astronomy: circular motion is not necessarily about the center; only the innermost orb of the moon, which describes the daily rotation, is about the earth; the other spheres rotate about layers of the body that does not preserve its shape, encompassed by these spheres.

160 Wars V.1.130; Goldstein's translation in "Levi ben Gerson's Theory of Planetary Distances," Centaurus 29 (1986) 287,29-288,32.

161 Freudenthal, "Cosmologie et Physique," 296. 162B. R. Goldstein, "Levi ben Gerson's Theory of Planetary Distances," 272-313;

"Levi ben Gerson's Contributions to Astronomy" in Studies on Gersonides, ed. Freu- denthal, 11-15.

163 Wars V.1.37, P 69b18; V.1.97, Q 142a37-bl.




When was the hypothesis of the body which does not preserve its shape first introduced? I did not find any reference to this concept in the super-commentaries on the physical writings of Aver- roes, which were written in 1321.164 This absence is not accidental, since there are contexts in which the hypothesis of the body which does not preserve its shape should be "expected," and its absence is conspicuous. 165

There is some evidence that this concept was not yet introduced by the end of 1325. The phrase ornzwn t):) (the bottles of the heavens, Job 38:37) is a central metaphor in the fifth book of the Wars and is mentioned several times. 166 It stands for "the spheres encompassing the body that does not preserve its shape" as they are filled with liquid or air which do not preserve their shapes. Neither this interpretation nor the term "body that does not preserve its shape," are mentioned in the commentary on Job completed at the end of 1325. 167

Similarly, there is no early mention of the theory of planetary distances based on the hypothesis of the body that does not preserve its shape. In the commentary on the Meteorology (from the end of

164 In the manuscripts listed in the Appendix. 165 I shall mention three such examples: (1) Gersonides discusses the possibility of

more than one world in his commentaries on De caelo and in the Wars. In the Wars he argues that if there were more than one world, what is between the worlds should be either corporeal or not. In the first case it should be either a body that preserves its shape or a body that does not preserve its shape (VI..l19, L 378). In the two commentaries on De caelo, the distinction, in the corporeal case, is between a physical and a mathematical body. In the Commentary on the Middle Commentary it is either the celestial body or a body that does not move, namely a mathematical body (ow )r-nw) (MS Parma 805, f. 30b22-24). In the Commentary on the Epitome it is either a natural or an unnatural body (Yivn )Pfl ov) (MS Paris 919, f. 190a4-10). (2) Ger- sonides discusses the principle that a rotating body rotates about another body in the commentaries and in the Wars. In the Wars he states that the body about which the spheres rotate is the body that does not preserve its shape (Wars V.1.43, Q 59b30- 31). In the Commentary on the Epitome of the Physics he states that this principle proves that the spheres rotate about each other (MS Berlin 110, f. 16b col. b31-32). (3) In the Commentary on the Epitome of the Meteorology Gersonides asks how it is possible that the sun moves the sublunar elements, but does not affect the motion of the mediating celestial spheres. When he discusses this subject, he does not mention the possibility that the sun's movement is blocked by the body that does not preserve its shape (MS Berlin 110, f. lOla col. b5-13).

166 Wars V.1.28, Q 33a32-33; V.1.37, P 69blO-11, 18-20; V.1.97, Q 142bl-5. 167 Gersonides, Commentary on Job (Ferrara) f. 105a; Miqra'ot Gedolot 5:192b.




1321) Ptolemy's values are quoted. 168 I have already mentioned Ger- sonides' second interpretation of the phrase "the height of the stars" in his commentary on Job (section 111.5 above). According to his first interpretation this term refers to "the height of the uppermost of the starred spheres, namely the sphere of the Zodiac." 169 In this context he remarks:

And he said this because due to their [the stars] being concealed by each other we know [which is] the uppermost, and due to the quanti- tative variance in their movements, we know what should be the min- imal possible distance of the celestial body, which is the first of all the starred spheres. And when we took this into consideration, from this as- pect, we found the height of these stars immensely great (mtx) orsv).* 70

This passage indicates that Gersonides was interested in planetary and stellar distances before the end of 1325, but there is not yet any allusion to the concept of layers of the body that does not preserve its shape between the spheres of adjacent planets. 171

Based on this (negative) evidence, I tend to conclude that the earlier version of the Wars did not include the concept of the body that does not preserve its shape,172 and to assume that this concept was developed sometime during the years 1326-1328. This assumption leads me to the third stage in the evolution of the Wars (mentioned at the beginning), namely the completion of Gersonides' cosmology and theory of creation.

168 In his Commentary on the Meteorology, written at the end of 1321, Gersonides estimates the distance of the sun "about 1000 earth radii" (MS Berlin 110, f. 130b col. a18-24). This is close to Ptolemy's estimate of the mean solar distance, which is 1210 earth radii, rather than to Gersonides' estimation in V.1.13 1 of the Wars, which is between 2052 and 2229 earth radii (Goldstein, "The Arabic Version of Ptolemy's Planetary Hypotheses," 11; "Levi ben Gerson's Theory of Planetary Distances," 285).

169 Commentary on Job (Ferrara) f. 59b, Miqra'ot Gedolot 5: 171a-b. 170 Commentary on Job (Ferrara) f. 61a, Miqra'ot Gedolot 5:172a. 171 Later Gersonides based his computation of stellar distances on this consider-

ation. See Goldstein, "Levi ben Gerson's Theory of Planetary Distances," 274. 172 We have seen that the first part of V. 1.43 includes early material and is referred

to in the commentaries on De caelo and the Meteorology. The hypothesis of the body that does not preserve its shape is mentioned towards the end of this chapter (Q 59b30). This does not mean, of course, that it was mentioned in the original version of this chapter.




IV. THE DEVELOPMENT OF THE

PHILOSOPHICAL-THEOLOGICAL PROJECT

Up to this point I have tried to follow the early preliminary stages of Gersonides' astronomical project and the corresponding development of his "eccentric cosmology." What was the state of the philosophical-theological project during this time?

According to his own testimony, Gersonides started working on his philosophical-theological project in 1317, at the age of 29.173 Relying on what we already know about the history of the astronomical project and on the references to book VI in the commentaries, I suggest that the theory of creation evolved in two stages. The first consisted of the argument with Aristotle. This argument (or at least a considerable part of it) was developed before 1321 and formed a major part of the early version of the Wars. The second stage, the construction of Gersonides' own theory, took place after 1326, and led to the completion of the sixth book of the Wars in 1329.

The references in the commentaries (on Averroes) to the sixth book are all to the chapters of the first part, in which Gersonides refutes Aristotle's theory of eternity and argues in philosophical terms for a theory of creation (see Appendix). It seems that the early version of the sixth book included an early version of chapters VI. 1.1- 16 and 20-28. There are no references in the commentaries to the presentation of Gersonides' own theory, expounded in chapter 17 of the first part, and in the second part of the sixth book.

Gersonides' theological and the astronomical projects were interrelated, perhaps already at this first stage. The complexity of the celestial motions is an "empirical demonstration" of creation. 174

Gersonides agrees with Plato that of the three possible accounts of creation-(1) by the agency of mind, or any god, or art (techne), (2) by nature (physis), (3) by chance 175-only the first can account for the complexity of the phenomena. He further works out this con- viction into philosophical arguments for creation. 176

173 Wars VI.1.29, L 417. See Feldman's introduction to The Wars, 1:55-58. 174 Wars V. 1.3, G 303,10-302,23. 175 Plato, Laws 889c. 176 Gersonides analyzes three properties of generated things (Wars VI. 1.6, L 308-

310): "A structure that is functionally or teleologically ordered, nonessential properties, or behaviour that is directed towards the perfection of other substances" (quoted from S. Feldman, "Gersonides' Proofs for the Creation of the Universe," Proceedings




It is quite clear that Gersonides did not regard his philosophical- theological project as accomplished at this stage. It seems that he set the philosophical-theological project aside, but went on working on the astronomical.

The second stage of the theological project, the detailed presentation of Gersonides' specific cosmogony, as I see it, was closely interrelated to the development of the astronomical project. Gersonides' theology and astronomy are deeply involved with each other through the hypothesis of the body that does not preserve its shape. 177 The existence of this body before the creation of the world is a basic premise of Gersonides' theology; its existence between the celestial spheres is a basic premise of his cosmology and essential for the justification of his eccentric astronomy. Thus, the introduction of the concept of the body that does not preserve its shape was a break- through for both projects. It concluded the "eccentric cosmology" of Book V.1 and also led to the development of Gersonides' original theory of cosmic distances. Adopting this hypothesis, Gersonides could also work out the details of his theory of creation, presented in chapter 17 of the first part of the sixth book, and in the second part.

After the development of the concept of the body that does not preserve its shape, Gersonides probably regarded his theological project as complete. It is likely that this motivated him to sign the book in 1329. We know, however, that he did not regard the astronomical project as complete, and went on working on it for many years (nn. 10-14 above).

V. CONCLUSION

From the commentaries on Averroes we have learned that the early version of the Wars was not only "a book especially dedicated to

of the American Academy for Jewish Research 35 (1976) 114; see also Staub, The Creation of the World 27-28). Celestial structure and movements exhibit these pat- terns, which indicate that the heavens are created. For example, the complexity of planetary motions, which is for the benefit of the earth, or the nonessential accidents, see as the different sizes or colors of the stars (Feldman, 114).

177 Concerning the role of the body that does not preserve its shape in Gersonides' theology, see S. Feldman, "Platonic Themes in Gersonides' Cosmology" in Salo Witt- mayer Baron Jubilee Volume (Jerusalem, 1975) 1:385-396; J. J. Staub, "Gersonides and Contemporary Theories on the Beginning of the World," Creation and the End of Days, ed. Novak and Samuelson, 247-248.




the investigation of the question of the eternity of the world," but also a reflection of the early steps of his astronomical project. These were, as I have suggested, significantly influenced by the argument with al-Bitruji, which helped Gersonides develop his own particular attitudes and methods. At this early stage, Gersonides tentatively accepted the eccentric model and worked on its justification. The process of justification was actually the formation of Gersonides' own cosmology. This "eccentric cosmology" formed an important part of the early version of the Wars. Both Gersonides' cosmology and his theory of creation were completed in the years 1328-29 following the introduction of the hypothesis of the body which does not preserve its shape. The work on the "astronomical part" of the astronomical project continued for many more years.

Gersonides claims that "our theorizing shouldfollow the empirical evidence," believing that mathematical astronomy is more reliable than natural science. His method indeed reflected this belief: the most "exact science," astronomy, determined the course of development of the more "theoretical science," cosmology, the major devi- ations from Aristotelian cosmology being motivated by astronomical considerations.

Historically, however, the development of Gersonides' natural philosophy was much faster than that of his astronomy. So, the theoretical justification of the eccentric model was completed long before he could measure, to his satisfaction, the eccentricity of the sun. So we see that though his views were in principle "Baconian," his work actually followed a more complex course, his astronomy, cosmology and theory of creation substantiating and being substantiated by each other.

APPENDIX

Listed below are the explicit references to the Wars of the Lord which I have located in the commentaries on Averroes' natural science. The list may be incomplete, as I have checked only one or two manuscripts of each commentary. The references are to the early versions of the Wars, which was not yet subdivided into books and parts of books. For convenience I refer (in parentheses) to chapter numbers of the extant redaction, though it would be more historically correct to refer to subjects discussed in the early version.




Commentary on the Epitome of the Physics. Colophon date: end of Sivan 81 (June 1321). MS Berlin 101/1 (IMHM 1801); MS Vatican 342/1 (IMHM 431).

(1) MS Berlin, f. 12a col. a3-10; MS Vatican, f. 24a9-10 (Wars VI. 1.1).

m)rte >nnn onz 1wn .11mvil

opf-IV xil-II

m95 125nn-11 zw )

)S9

1993 )D N 1X3Nvo-1 nnz O)mvwl n,715n IN''o-11 mnol 1.Xl jmmwn mon 5N Im

(2) MS Berlin, f. 45b col. b6-13; MS Vatican, f. 90a4-9 (colophon).

.mo-17 nII NtZ )DD1 O-m 1)n .1amnvollzmn 1-311131pn )r .r^ n NtZ 1X 05)W lx:)l 'im nivurn i5xv vixi owr ,rnvnn mit5 i35 -rni)) iôv in i))wY) in-r rm ): o5wn

.o)), 5)z 5v iwpin)o ormn) nn) x5 o5 v-n mwrj ivvix o-mo zn)

Commentary on the Middle Commentary on the Physics. Colophon date: Tamuz 81 (June-July 1321). MS Paris 964 (IMHM 31361).

(1) ff. l9bl7-20a21; see discussion of this passage: Harvey, "Absolute Generation of Prime Matter" (n. 19 above).

O' -#Tlr .-'in-n 'im w-rin , wx xi)i prnwflll l')f 11-f mnr nnz .ni. fl'vly flM rON -wlmnx lrn t -1115 -menn w-rin -wx xin ni-nwn >z )) 5izz-il nxivo ,enn

O)-)It-1 5)5 )51 )-115- xi-lI -o 'wn-n -m -wn -wxwn i nit . .. min x o-rp n.,)

IN.-)I .-t-1nu -tv ow)l -111n1m -vin-n rntzve) 5),wn) xii- rm5i) nrO n tn n m5z -wx )) m)n5e) roz -),) -nin 3nvi mmiz oipwn -nin pôv- -1 rim-1

(2) f. 45a3-13 (Wars VI.1.11).

,vofn l nx lOT IN fl 0 ) -W ,1 ip fle f') "' fl .1tv)0 lft'2 -tv 51Ol 1 .T . I 'r 2 fl1

n))in) rnwn rnopnl )

mirm n

13m ar v lxmn,1. ...n 50n)z rn

.w nn m tn nnn )"nv5n

(3) f. 86b11-24 (Wars VI.1.21, L 389). n' -n5nnn 'fl v 5f flfl)) y fl'f') 0) 1))Iw X5 nti)I N5Nh Nswf r1mVfl 1'XV) )'n) 05'ThI

I2r I ... 'vflm Xqw fnY OW ofw n'Vnfl2 xinn l f1mVY) '13)mo 1))n) 2"V . . .tn) .wn nre)e rôznwnr -5tv 13irznvil

(4) f. 131blO-14 (Wars V1.1.24). X5 rvl)n ow) Xm-n x5w -)ff 0,)z .)z 5,v 1))In) -m I)XV) )) nmmn)0 -),)V wwnx -a, flV~flT1 OW

.?II 5'W o"1 ,Ornfl t 1' -,III fIpl Oip)W '"

fl1 1w') w lflt'2

-flV2Pm ill ))J OW 0)z12h rO1N 'O i112 fl1)pnf orp infl l .flvPW1 fl) OrTjp

(5) f. 132a3-6 (Wars VI.1.21). mvy OW fl'f Ox fl1 .~fprnpnW fl) ae ))Etf lrDnzW inv) flij" oe fiW rfl1)R 123

ON) 1-1nDe roz ts rtntet?rznlrrr.zur o

5nru)




(6) f. 132b26-133al5 (Wars VI.1.24, L 399-400). n3w 1VVz Wo)x Intal1l oxi .11'nx wn-11 15 Ns w^w lXw -ton.' 13n)XV) 5won1r flV Mr)f21fl 12. ... orrTt? ))wo2 5'V Inrnntin flip) . . . t'flfl 1Inx Wnifl nrl1wo Ttv'w9 1

.'" n rvzonn - fn rnzXnn

(7) f. 145a4-9 (Wars VI.1.22, L 390; VI.1.24, L 399).

nwi n- -)N o)'Nm .Ir m -rn ON ,o0vn mV1n'n I)rnv. rnD 'nn 'm- I) o-rp") X ON ni

Commentary on the Epitome of De Caelo. Colophon date: Elul 81 (August-September 1321). MS Paris 919 (IMHM 30913); MS Berlin 110/2 (IMHM 1801).

(1) MS Paris, f. 175al7-19; MS Berlin, f. 52a col. b32-52b col. a3 (Wars VI.1.26). ,i:i ,n n5 vo .-rm a) x5 -i-nrn x5v ixne n ,X- "Nn-1w ret,1n wnewl oV)5 I)XV ).0

(2) MS Paris, f. 192b20-21; MS Berlin, f. 63a col. a17-18 (perhaps Wars VI.1.4). Inx):Iw )n ,t) n Iz ))ZAlA n5in -'r-1W t)Ix' -m-1 -Irrpm nnzpn 'II)oN mil-II

MIz IUINa I'1)0w '11M :1))n) x5v Iznxn owi . nxipn -mtarwn )) nvon5n 'iom

Irn))nt))M111 .nn w-11 n svnmp -I1. rnanz W)w ow Iznxz): ,rn5 n) 5 ofVn 1n

(3) MS Paris, f. 197bl2-15; MS Berlin, f. 66a col. a9-14 (Wars VI.1.9, L 323). ,)Na .-I'Vmiln mn5nm ImnD -IN' wx oipwn j)wI -mn vonD plnwi- -rvi jIx vo) 1:' li

(4) MS Paris, ff. 201b25-202al; MS Berlin, f. 68b col. b3-6 (Wars V.1.44, Q 61bl5- 17; see section 11.1 above). 5m O'Dvn) ' [nvwn mn5n fYn fw] w'nn nwItnI I)V ')) nvronn 1.0m mm Ini1a' 12Or

.ovn5o 15nno az o)IOn:n nsp 5-rvo win:i -svo

(5) MS Paris, f. 204a20-23; MS Berlin f. 70a col. a 25-31 (perhaps V.2.5, L 202). :)">) rl5' Inw rurn) nz rzw-I IlO n r oxw .11rzV orp17e -,I .-II) )V1,1 II V)w I)ON) W)OV

.5DUry lx I10 n)'w nlI-1 15MA)f

(6) and (7) MS Paris, f. 213a9-23; MS Berlin, ff. 75b col. b8-76a col. al (Wars V.1.28, Q 32b33-33a2; see section 111.4 above). nlI'sv )vnw f nw ' n ,)fln2mfl n -rsn l'') -m fX v on" i nYin mor2n -n1m.. -srm ox

wiOwnOwimYl p-rN)xI nm w mlY 5: nwoomn ,nnvA Jimn mnt r)v)t Yvt YnivYtm:

11)-11) :1))rI)w t).0 ,jm:1-1 A)5)5 rtNw -nm-nn nxi5 ii)nn) mlrnAn- -nD -,wii . .. oznxn5

I))nn)w -mo 'iinv) xV2x i)rnwt) x r nwm i) rtnin Imn Ivxe nwi<miltm ftzI vvtmo




nvonen'l oz zran :nn z) >z zw J rz ox v:iu-' 1YI M 1W

0)wnn)-11 15M Y rv:1 -m-i lv 08nx Ivx ovirr-n im5)iy v-rn Y ix'i ovi:rr-nn l1D.v

,0 no v 0IW:1 0-1vo fJ 1TniniY nlpov rnA'v'1 , ) fY o)2lnV 'T2 tin [oti"n2 n]

2" 1nTnh2CL '1rV vnIv rn

(8) MS Paris, f. 217a5-12; MS Berlin, f. 78a col. bl-13 (the reference is to V.1.43, Q 56a4-33).

5y 1VYn1 511 pn1 oti2)f fln Ynn W.)fl xi1 -rrn1v . ... I2Y nv ivo) -m wo i1vYn5

otui -Nr?- no WIVN Otiv)'rtO JmI -rv im wntin5Y nw' o) Otiow- 1i ox -tm mmOti)2)o tD

.nrnnn nr ay 5p v'v iv v rnipov vminm "op nro i,orvn

(9) MS Paris, f. 220b16-19; MS Berlin, f. 80b col. al-5 (Wars V1.1.13; as to the statement that what is accidental cannot be eternal, see VI.1.6, L 309). InNITl'i 0v P)0:1 mll'w -III)i re ya m5)fn] i-iw Atwtvmx) -rwn 1:ix)D) Irv oipn jxt35n rnz v-nmo o5v-n mnvn 5-m -nipn [nqp 5t rr] n t m irn ivi r nwom Y rpn:j

-

.1$YPpn2 Y u hm1 oupY .fl I)Xm n2 1vn 5lof1W rv1xVW

(10) MS Paris, f. 226bl2-14; MS Berlin, f. 84a col. a13-16 (the reference is to V.1.43, Q 56a4-33). YYvzm) I:1W -II)o 5m vn):1 5'1p) vvlmotli 'i:i'tpn -srhmv 12 ,5p2ml n2r:oz tnvimsi 12 m . T

.)) rn 9D nvo5 1m-1: 'vomon 1:1znn '11z)I .-mz i

Commentary on the Middle Commentary on De Caelo. MS Parma R. 805 (IMHM 13659). This text is extant in only one manuscript, which is incomplete and undated.178

(1) f. 13bl-4 (fols. numbered from the beginning of the text) (Wars VI.1.26). n)) .-mm x5i min-rirn x5v jf o-n i5 I)XV -010: :1))nn ln)v ')) nvonn5n 'lom vix):1 '1:z

.11r0rp )mw wenom > 0-): ne :1))Im I rm I5'x:1) tIN ,ow 1),V) 'm moxa 5Y'rv't)0'v5

Commentary on the Epitome of the Generation and Corruption. Colophon date: Elul 81 (August-September 1321). MS Berlin 110/3 (IMHM 1801); MS Vatican 342/3 (IMHM 431). No explicit references.

Commentary on the Epitome of the Meteorology. Colophon date: Tevet 82 (Decem- ber 1321). MS Berlin 110/4 (IMHM 1801).

(1) f. 101b col. a17-21 (Wars V.2.6). M5rn fv nisnntn ntnvt trm ,5 v Y fot ymn rnt ivac rmv' [vnwn fw] tinn mtntz

ro nv tmm nv o) nvon5nln mnu oxwn -rv nmnnni iin .rn M vp rnnnji mx rnn?n

m.ip mnrx1 rtn

178 R. Glasner, "An Unknown Commentary by Gersonides" (Hebrew), Qiryat Sefer 64 (1992/3) 1101.




(2) and (3) f. 106a col. b16, 22 (Wars V.1.43, Q 56b22-31; V.1.51 Q 76b19-24; V.2.9, L 217).

nar'z ,prz nnr~m r

xia n n9-z i imnnn i2uM .npvn w'fz r

v mnn rz

rvnD nr1

i2~ ,nin af ,1-rn ~m~v -~mme 1p1 o np Irn Vrr 5 0fl)o .I). miv 1 Ilm mnn I mvv wnvin -*i-rz nm&n nzn my an mm inmv m>f v nnp , n rer irz n mzpnn aV

(4) f. 11 2a col. a23-28 (Wars VI. 1 15). x5v iv rnn inv i-rmw)n Ironn)V ,'o) nvn'm ) ' tn nvw 1 nmn lx '1v 1w -1 f

inrtrtr nzI ,mvn vr5rpn rnv- t ' nl2 .om n tvn5n ra rv' - mi

mon 52nClo 1oV

(5) f. 117a col. b26-29 (Wars VI.1.9, L 324-326).

ofln iX?w1 2l9nT 1'T1' 'Thw iflY "rz fl YL ran2 1 wrVn rmr

ni1n 1 ma. 1 ) flr1T1a

(6) f. 120b col. b19-28 (the reference is to VI.1.14, L 352). i5m orni ,vonn inv-rwn wovn) oi- .m 5,n ?Y o x -rv mnown rsn ni w m

In -115n-l Oipwl l -m mm-1 nvn -sinn nxi i . . . -r:i mow xi-nv -svn x5,o ozzn~n

'IWJOx aw XV OWi 1)) nvon5n 'Iov: -,II A nV51n:1 InOND 1:1:) ,) 15 I yNa

,-im) o):rnD) mrl)nosn -mnow -rvi I:ix5 ir-nn ox mmnORw -sm :irmiA p-r 51 mv12 o5vnv n5vin r) ,ow -nn o):rr-n iz5 iznx 1::)l )nos-llo )Nml -1)11v) 1m-11 nnzma o). :mn) -m-1

(7) f. 123a col. b6-7 (Wars V.1.43, Q 56a4-33). 1Vw 1 '1 )XnriM n mo m 5p mn5m ,12n rmp )noM -m A,m nnniv m 0 vnn v) imr

vix:iw vz rznnn -p-n n)r) x5 -ro-m r5v -r:r) nz) pn x5 5pnr 1.0-i IN Ox D v-Ivnnm)

1)) mrn)n 1Dz zn 1raz1XnAl,O)lY) Ov-II 'I.Om



The Early Stages in the Evolution of The Wars of the Lord

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Transcript of The Early Stages in the Evolution of The Wars of the Lord