In this article the author analyzes a fifteenth-century Arabic reform of the Ptolemaic model for Mercury. The author of the reform was the Central Asian – Ottoman astronomer ‘Alā” al-Dīn al-Qushjī (d. 1474 A.D.) who, in his youth, had been instructed in the mathematical sciences by none other than the famous Central Asian monarch Ulugh Beg (1394–1449). Although the astronomers of Ulugh Beg's circle are known to have produced extensive astronomical Persian tables, no one other than Qushjī has been yet identified to have produced a theoretical text devoted to the criticism, let alone the reform, of the Ptolemaic mathematical planetary models. The present article on Qushji's reform of the Ptolemaic model for Mercury includes a critical first edition of Qushji's Arabic text, an English translation, and a historical and technical commentary.

The author examines the relationship between mathematics and philosophy in the works of al-Kindī, and suggests that the real character of his contribution will become clear only when we restore to mathematics their proper role in his philosophy. The recently discovered treatise of al-Kindī on the approximation of π, of which the author gives the editio princeps here, throws important new light on al-Kindī's knowledge of mathematics, and on the history of the transmission of The Measurement of the Circle of Archimedes. The author shows that al-Kindī's commentary on the third proposition of the Measurement of the Circle was written before 857, at the same time if not before that of the Banū Mūsā, and that it was one of the sources of the Florence Versions, the Latin commentary on the same proposition.

Al-Kindī's views concerning time are dispersed in different places in his works, but they are to be found principally in his On First Philosophy and De quinque essentiis (Sermo de tempore). Yes, he does follow Aristotle, but he insists on the homogeneity of the instant and of time; he also distances himself from the Philosopher by denying the eternity of the world a parte ante as well as a parte post. On the other hand, in his accounts of the realization of possible things and of the organization of the cosmos, he presents certain views that sometimes tend toward the principle of plenitude, and sometimes toward the doctrine of the best possible world, and here one can discern a principle that is distinctly theological.

The article describes several representations of Alexander the Great which were current in medieval Arabic learned circles and proposes some ideas on the genesis of these representations in the Greek and Syriac civilizations: 1) Alexander as moralist; 2) Alexander as a mystical philosopher who knew the mysterious links governing the cosmos; 3) Alexander as a monotheist philosopher who was charged with responsibility for the Ğihād; 4) Alexander as a cunning politician.

In his commentary on the first Aphorism of Hippocrates Maimonides lists the seven parts of medicine. Scholars have studied the relation of this text to the work of al-Fārābī. In particular, they have focused on the Iḥṣāʼ al-ʼulῡm, which in its present form does not contain a discussion of medicine, and on al-Fārābīʼs Risāla fi al-ţibb. The article examines the medieval Hebrew versions of the Iḥṣāʼ al-ʽūlum (versions made by Falaqera, Qalonimos and Rieti). On the basis of these versions, it is argued that there existed a version of the Ihşāʼ al-ʽulūm which did contain a section on medicine; that the Risala fi al-ţibb could have originated in such a fuller version of the Ihsa' al-'ulum; and that Maimonides's ultimate source for his classification of medicine was probably the Iḥṣāʼ al-ʽulūm. An appendix to the paper examines Maimonides's references to Galen and to Abū Bakr al- Rāzī. These references show Maimonides's perception of al-Fārābīʼs view of physicians who claim to be philosophers.

Al-Kindī's Forty Chapters was one of the most influential astrological texts in the Middle Ages in the Arabic and Latin-reading world. Yet it has never been studied by modern scholars and has not even been properly identified in the standard bibliographies and encyclopaedias of Arabic literature. This study describes the work as it appears in the Arabic MS, Jerusalem, Khālidī Library, 21(2)-Astr.-2; sets it in the tradition of Greek, Persian and Arabic texts on catarchic astrology; and traces its influence on later Arabic astrological works, which give evidence of a fuller text than that in the Khālidī Library. This fuller text appears in the two Latin translations made in the mid-twelfth century by Hugo of Santalla and Robert of Ketton. Finally some comments are added about the place of The Forty Chapters in al-Kindī's œ;uvre. Two appendixes give respectively details of the manuscripts of the Arabic text and the two Latin translations, and an edition of a specimen chapter (concerning irrigation and cultivating the land) from these three versions.

How do the heavenly bodies physically affect the sublunary world? On this topic, the few fragmentary statements by Aristotle were refined and expanded by his Greek commentator Alexander of Aphrodisias. In the Kindī-circle, particular attention was paid to Alexander's treatises on this very topic. They were not simply translated but were rather reworked in terms of an astrological interpretation. Typically, such reworking was attributed directly to Aristotle by the addition of a number of references and pseudo-references to Aristotle's genuine and spurious works. The article demonstrates this phenomenon, and examines the circular relationship between the Kindī-circle adaptations of Alexander and al-Kindī's own works. The Kindī-circle's Alexander was closely followed by al-Kindī on certain points, while al-Kindī himself exerted a reciprocal influence on the Arabic Alexander, who was largely the product of his own group of translators. The appendix contains English translations from Arabic of two adapted Alexander's treatises.

This paper presents the Arabic text, the French translation and an analysis of al-Sijzīʼs treatise (second half of the tenth century), the Book of Measurement of Spheres by Spheres. In this text, al-Sijzī divides the cube into several sub-cubes and parallelopipedes, thus offering us a stereometric interpretation of algebraic identities of the third degree usually credited to mathematicians of the sixteenth and seventeenth centuries. However, this was not al-Sijzīʼs motivation for writing this treatise; rather it was his theoretical interest in the Euclidian concept of the “power” of a segment, an interest which is clearly geometric rather than algebraic. This has led al-Sijzī to the notion of dimension, at least in outline.