Of course, that the Aragonese kingdom drew much of its wealth and prestige from maritime trade and exploration was clearly a factor in the courtly interest in such maps and charts. But in the case of late medieval Iberian Jews, the role of the court in shaping scientific activity seems to have been more direct. Jewish astronomers, physicians, astrologers, instrument makers, clockmakers, and more were all employed by the Iberian monarchs, and royal interest in their skills was precisely what enabled their scientific activity. Jacob Bonjorn, though we know relatively little about him other than his astronomical tables, seems himself to have been a beneficiary of such royal patronage at the Aragonese court in Perpignan.
Joan I’s court was particularly open to the occult and to astrological divination. Profayt Duran’s appointment as astrologer reflects that openness. The skills needed for the practice of astrology—namely, knowledge of the principles of astronomy, the use of observational instruments, and the reading of astronomical tables—are precisely what some of Duran’s students were interested in.35 In the medieval Islamic world, too, scientific work was done for “rulers whose primary interests lay in the practical benefits promised by the practitioners of medicine and astronomy and astrology and applied mathematics.”36 Reflected very clearly in the class notes discussed above are both the technical nature of the science being imparted and the pragmatic nature of what appear to be the students’ scientific ambitions, as well as the fact that they were engaged in using and understanding astronomical tables. Duran’s teaching activities in these documents are thus emblematic of the kind of extrauniversity transmission of knowledge, court patronage, and utilitarian focus that seems to have characterized Iberian science (both Jewish and non-Jewish) at this period. Yet as we will see in Chapter 5, Duran’s scientific correspondence with peers also reflects a nonpragmatic preoccupation—for example, with the relation between the mathematical models of the heavens and sensible reality—that seems to stem from more theoretical and possibly theological concerns. In fact, Duran engaged in scientific activity at many levels, reflecting the interplay of social and economic factors with theological rationalizations and issues of Jewish identity.
One commonly recognized characteristic of the sciences in the Iberian Peninsula is their continued reliance on Arabic astronomy well into the sixteenth century, a conservatism usually attributed to the area’s geographical proximity to North Africa and to what has been called “indelible Arabic cultural influences.”37 In the case of Duran, it is important to point out that Catalonia had no history of Muslim domination, or significant Muslim population. Still, the same conservative impulse has also been associated with Jewish and converso prominence in these fields, since, wherever in Iberia they lived, Jews were presumably the custodians of Arabic science. Indeed, recent quantitative studies confirm a decided preference among Jewish scholars for Arabic over Latin sources when it came to translating philosophical and scientific texts into Hebrew, a preference holding steady in Iberia up to the fifteenth century, when there appears a flurry of Hebrew translations of Latin philosophical texts.38
On this point, what Duran and his students were studying is entirely congruent with the common perception. Apart from the obvious Ptolemy, their sources can be categorized as primarily ninth- through twelfth-century Arabic writers: al-Farghānī, al-Farabi, ibn Sina, ibn Aflaḥ, and ibn Rushd. These basic texts were supplemented by two twelfth-century Iberian 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