Some of the short pieces attributed in various Arabic manuscripts to Alexander of Aphrodisias in fact derive from Proclus's Elements of Theology. Twenty such pieces were published in 1973 by G. Endress, who traced the unnamed translator to the circle of Kindi. Another such piece is here identified, published, and assigned to the same translator. Its beginning and end seem to have been revised by a later transmitter. Section II of the article adduces a parallel case where the original Arabic version still exists. Section III surveys a number of related pieces that would also appear to have been changed in transmission. Section IV argues that most if not all were once united in a single collection of Proclus and Alexander. Section V argues that since certain changes of detail were evidently made during or soon after translation, the general arrangement of the Kindi-circle Alexander, as of the Kindi-circle Liber de Causis and the Kindi-circle “Theology of Aristotle”, is also likely to be peculiar to the Arabic tradition. The text from which Proclus Arabus was first translated need not have differed substantially from the transmitted Greek.

In this paper, are included new data about three treatises ascribed in Arabic to Alexander of Aphrodisias. These treatises were thought to have no Greek correspondent. The author shows that one of them, (D.8a), is an adapted version – following the norms of “al-Kindi circle” – of Quaestio I 21, along with the later and more exact version of this Quaestio by Abū ‘Uṭmān al-Dimašqi (d. 900). He shows also that the two other treatises (D.9 and D.16) are, in contradistinction to the first, adapted versions of passages belonging in the De Aeternitate mundi contra Proclum of John Philoponus: respectively IV, 4–6 and IX, 11. Philoponus’ book was known to have been translated, into Arabic. But, except for some short fragments in al-Bīrūnī (d. 1048), it seems that it is the first time that important adapted extracts of it are put in light. Some points are made about the historical position of the epitomator of these passages. In Appendix II, another treatise ascribed to Alexander (D.27g) appears – provisionally – as a composite text, mixing elements coming from Philoponus and others from neoplatonic texts in Arabic. In Appendix III is analysed the use of D.16 by Miskawayh (d. 1030), and the use of D.27g by ‘Abdallaṭīf al-Baġdādī (d. 1231).

Ṯābit b. Qurra is especially known as a mathematician, but his work in astronomy is also important. This article reviews his eight surviving astronomical treatises, as well as relevant fragments of his lost works cited by later authors in Arabic and Latin. We conclude that, as an active participant in the scientific movement of 9th-century Baghdad, Ṯābit played a crucial role in the establishment of astronomy as an exact science. The argument is based on an assessment of his contribution in three areas: the relationship between observation and theory, the “mathematization” of astronomy, and the relationship between “mathematical” astronomy and “physical” astronomy.

The scholastic doctrine of transcendentals is inherited from Arabic philosophy to a certain extent. This dependance is clearly illustrated in the construction of the problematic of the transcendental one, which is identical with being, and of the numerical one, which is not. The scholastic discussion as a whole reproduces the major themes of Avicenna's position, then of Averroes' criticism of Avicenna. This article attempts to reconstruct the complex of questions, topics, and arguments which constitute this problematic by tracing its evolution through the analysis of anonymous sophismata and of texts by Nicholas of Paris, Roger Bacon, Albert the Great, and James of Viterbo. Two stages are distinguished: the first is centered on the distinction between the transcendental and numerical one; the second, essentially German (Dietrich of Freiberg and Berthold of Moosburg), is centered on the subordination of the Aristotelian to the Platonic concept of the transcendental one. Along the way, it is shown that, with the exception of the German philosophers, the understanding of Avicenna's position is constantly filtered through Averroes' interpretation.

Euclid's definition of proportional magnitudes in the Fifth Book of the Elements gave rise to many commentaries. We examine closely two of these commentaries, one by al-Jayyānī (11th century) and the other by Saunderson (18th century). Both al-Jayyānī and Saunderson attempted to defend Euclid's definition by making explicit what Euclid had only implied. We show that the two authors explain Euclid's position in a virtually identical manner.