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.

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.