Jewish astronomers, Abraham bar Ḥiyya and Abraham ibn Ezra. Finally, their contemporary (fourteenth-century) sources were also Jews: Levi ben Gerson and Jacob ben David Bonjorn. There is little sign of any knowledge of or interest in current Latin astronomy.
A single exception to the rule lies in a commentary by Duran on a short treatise on asymptotes called On Two Lines, which was probably translated into Hebrew from Arabic at the beginning of the fourteenth century.39 Duran’s commentary exists in two manuscripts, and has itself been shown to rely heavily on a Latin paraphrase of the Latin version of On Two Lines.40 That Duran’s scientific writings do not quote Latin astronomers thus does not mean he was not reading Latin scientific works, but it does suggest that in his view, as far as contemporary astronomy was concerned, the finest work was being done by Jews: Gersonides and Jacob Bonjorn in particular.
In passing I must note that Duran’s interest in the question of asymptotes seems to have arisen from his study of Maimonides’ Guide of the Perplexed; there Maimonides mentions the concept of two lines that approach each other infinitely closely, but never actually touch, as being in the category of things that are ungraspable but true.41 Duran explicates this point in Guide I.73 in a passage that has been shown to be taken nearly exactly from a text attributed to Jacob Bonjorn and found in one manuscript of his Astronomical Tables.42 The passage has been described as “confused,” and Duran may have thought that he needed further explication of the question, spurring him to read the treatise On Two Lines and assimilate the material of the Latin paraphrase.
To recapitulate briefly: from the traces of the scientific activity of Duran and his students left in their notebooks and letters, manuscripts and marginalia, we have learned a certain amount about the methods of scientific teaching and study undertaken in Jewish communities outside the university setting. These students shared material from books and notebooks. They studied manuscripts together and recorded the comments of their teacher in the margins. Sometimes the glosses might be incorporated into and become part of the transmitted text, or sometimes the students might shape their informal marginal glosses into a formal commentary, copied independently of the text. In many cases, students paid careful attention to and noted down the reliability of their sources of information. Our exploration of the scientific activity of these groups of Jews illustrates not the production of new knowledge or new texts but another aspect of Jewish scientific activity: the transmission and consumption of known science.
In John E. Murdoch’s view, “the predominant social factor effecting intellectual development and change in the Middle Ages [was] the university.”43 While Jewish scholarship was not entirely divorced from university learning, a very different dynamic was at work in determining the direction of its scientific and philosophical investigation. Murdoch has also argued for what he calls “the unitary character of late medieval learning,” by which he means that theological issues were closely linked to the questions pursued in natural philosophy; in the institutional setting of the university, the various schools were in conversation with each other.44 As for the Iberian Jewish intellectual elite, its members were neither attached to a university nor entirely independent from each other. By means of the communication networks of scholarly epistles and the circulation of manuscripts, they were able to engage in issues of common interest. The settings where Jewish knowledge transmission took place were flexible and varied, ranging from study groups that could mix correspondence and personal encounter to exchanges of formal essay-like letters among groups of peers who shared questions and concerns. These networks of communication share some characteristics with the circulation of rabbinic responsa, exchanged by figures who typically knew each other, often by means of designated couriers. In certain respects, the two may indeed be considered parallel phenomena.45
Transmission of information among Jews was thus largely ad hoc, responding to the interests and needs of individuals rather than to a set curriculum. What spurred these interests could vary from a practical need for valued technical skills to the intellectual need for careful exploration of lines of scientific or mathematical research, in this case often suggested by Maimonides. Indeed, for Duran and his circle, and for the Iberian Jewish rationalist elite as a whole, I would suggest that Maimonides’ Guide served as a base text, shaping the interests and motivations of Jewish scholars in a manner parallel to the way in which the Christian university curriculum shaped the interests and motivations of Christian scholars. Just as within the university context theological concerns could impress themselves on the study of natural philosophy, so too the intensive study of Maimonides tended to filter science through the lens of the master’s theological considerations.46
As we will see, this is also very much true of Jewish philosophy as a whole.
CHAPTER 3
Efodi
The Commentary on the Guide of the Perplexed
In the seventeenth century, Joseph Solomon Delmedigo (1591–1655) reported in a letter that while in Egypt he had seen something like eighteen commentaries on the Guide, long and short. He classified four of them by reference to the four sons of the Passover haggadah. One was by “Efodi,” a variation of the name Efod that was used to refer to Duran beginning sometime in the fifteenth century. Delmedigo’s evaluation of Duran as the son “who does not ask” sounds at first negative. But in fact Delmedigo is not pleased with radical commentators, like Moses Narboni, who inquire too deeply into Maimonides’ secret positions and reveal them indiscriminately. For him, it would seem, the best commentator is one who explains the plain meaning of the text. He goes on: “Efodi, who is an honorable man, answers the unstated question [lit. answers the mute: meshiv ḥeresh] and, like Rashi, does not ask, [and he does so] briefly and clearly; he is the principal commentator [on the Guide] and he belongs in the category of mathematicians and astronomers.”1 In this description, Delmedigo has put his finger on two real characteristics of Duran’s commentary: first, his responsiveness to difficulties in the text and the central fact that many of his glosses are primarily aimed at clarification; second, the salience of Duran’s mathematical and astronomical interests.
The quality of “not asking,” which Delmedigo sees as similar to Rashi, is that Duran may respond to a problem in the text but he will not tell you explicitly what that problem is. For each comment, one might well ask: “what is bothering Efodi?” Sometimes the problem is merely one of Tibbonide awkwardness; Duran simply restates a difficult sentence in clearer syntactical form. For example, the Guide opens with these words (in Pines’s translation from the Arabic) to Joseph, the work’s addressee: “When you came to me, having conceived the intention of journeying from the country farthest away in order to read texts under my guidance….”2 In the Hebrew translation by Samuel ibn Tibbon (c. 1150–c. 1230), the text on which Duran bases his commentary, it comes out something like this: “Behold from then you came to me, and you intended from the ends of the earth to read before me….”3 Duran glosses as follows: “from then you came to me: he means from an earlier time, when it was your intention to come before me; and you intended: he explains, before you came to me, your intention was to come.”4 Here it is not a question of points of doctrine; it is merely a matter of clarifying the sometimes turgid, sometimes knotty style of the Hebrew translation.
Of course, there is more to Duran’s commentary than clarification. While he does not seem to come to the text with a fully thought out system of his own, he does make numerous substantive comments reflecting his interpretive lens. He does not hesitate in general to add information, usually in a neutral (“not asking”) voice, explaining (or enlarging on) what he thinks Maimonides truly meant to say.
As for the astronomical and mathematical interests, it is likely Delmedigo knew Duran’s scientific writings apart from the commentary on the Guide. The astronomical knowledge to be found in the commentary is of no more than minor significance, and would hardly warrant
