Dans l'introduction à un texte majeur consacré à la composition des rapports et dans lequel on s'accorde à voir un pas important dans l'élaboration de la notion de nombre irrationnel, al-Khayyām remarque:

La diffusion d'Alexandre d'Aphrodise, en raison de la qualité inégalée de son exégèse d'Aristote, est celle des textes vivants. Simplicius est plus érudit, Philopon plus critique, Averroès plus savant. Mais Alexandre possédait un art de la synthèse entre l'analyse philologique de la lettre et la saisie de l'orientation générale d'un texte, qui fait de lui l'Exégète par excellence. On comprend, dans ces conditions, que sa transmission ne soit pas le relais linéaire d'un ‘‘témoin” figé. Citons aussi bien le recours extensif de Simplicius, au VIe siècle, à ses commentaires physiques que la renaissance philosophique des IXe–Xe siècles en terre d’Islam, qui s'accompagne d'un mouvement massif de traduction de textes alexandriques. Or s'il apparaît de plus en plus clairement que c'est la nécessité de bâtir une ontologie du sensible aristotélicienne, subordonnée à l'ontologie platonicienne des Formes divines, qui a poussé le ‘‘platonicien” Simplicius à puiser dans les commentaires de son prédécesseur, on ne s’est pas encore assez interrogé sur le sens de l'intérêt aigu des philosophes islamiques pour Alexandre. Pourquoi, par exemple, alors que les Byzantins, quand ils ont eu le choix entre Alexandre et Simplicius, ont choisi Simplicius, les Arabes se sont-ils systématiquement décidés pour Alexandre?

The Liber de compositione alchemiae or the The Book of the Composition of Alchemy is believed to have been the first book on alchemy that was translated from Arabic into Latin. The translator was the Englishman Robert of Chester who was one of the earliest translators to flock to Spain to learn Arabic and to translate some of the Arabic works. He completed his translation on 11 February, 1144.

Most scholars of Islamic intellectual history now agree on the distortedness of the traditional Western portrayal of al-Ġazālī (d. 1111) as the defender of Muslim orthodoxy whose Incoherence of the Philosophers (Tahāfut al-falāsifa) was such a powerful critique that it caused the annihilation of philosophical activity in Islamic civilization. Some in fact are coming to the conclusion that al-Ġazālī's importance in the history of Islamic philosophy and theology derives as much from his assiduous incorporation of basic metaphysical ideas into central doctrines of Sunnī kalām, as from his far more celebrated bashing of the falāsifa. What is less well known is that al-Ġazālī's role in the ‘‘philosophizing” of Sunnī theology was not a lonely struggle by a single genius, but part of a broader trend that seems to have begun during Avicenna’s lifetime and that picked up speed in the first and second generations after Avicenna's death in 1037, with the work of al-Ġazālī's teacher, the Aš‘arite al-Gˇuwaynī (d. 1085), as well as of the Māturīdite al-Bazdawī (d. 1099), work that was carried forward by dozens of subsequent members of those two major Sunnī theological schools. It is clear, in fact, that the dividing line between the Sunnī theologians commonly referred to in the later Islamic tradition as mutaqaddimūn (‘‘early” or ‘‘ancient”), and those referred to as muta’aḫhḫirūn (‘‘late” or ‘‘modern”), lies not with al-Ġazālī but with Avicenna himself, and that the turn in Sunnī kalām was therefore Avicennian, not Ġazālian.

Ibn Sarābiyūn is one of the last exponents of classical Syriac medical writing, and one of the most influential authors for the development of medical theory and practice in late ninth-century Baghdad in particular, and for the Arabic medical tradition in general. During the last thirty years, three important studies have been published regarding the life and work of Ibn Sarābiyūn, each of which dealing with a different aspect of the transmission of this important author’s œuvre. Likewise, during the last twenty-five years, a number of texts associated with Ibn Sarābiyūn's works have been edited, allowing us today to shed new light on the relation between the original Syriac and the numerous translations into Arabic, Latin and Hebrew. Furthermore, through analysing and comparing a number of manuscripts containing different parts of Ibn Sarābiyūn's work which have not hitherto been considered together, progress can be made towards answering the question how Ibn Sarābiyūn was translated and used during the medieval period.

The traditional argument of Muslim theologians that aims to verify the claims of a true prophet and distinguish him from an impostor is based on the acceptance of miracles performed in history and testified through an uninterrupted chain of tradition (tawātur). A second argument that equally involves transmission through tawātur is based on the prophet’s virtuous and impeccable character establishing the trustworthiness (sidq) of the prophet. These are, for instance, the types of proofs (singl. huˇgˇga) mentioned by the Baghdadian Mu‘tazilī al-Gˇāhiz (d. 255/869) in his monograph Huˇgaˇg al-nubuwwa. For theologians of the Aš‘arite school this approach to the verification of prophecy posed a problem. According to classical Aš‘arite theology, good is what God commands and bad is what he forbids. If God chooses prophets to reveal knowledge about what is right and what is wrong, and thus also reveal knowledge about how to live a virtuous life, how can those whom the prophets call upon know that the prophets have a virtuous character before they even know the criteria for virtue? Early Aš‘arite theologians indeed accepted that all prophets had a most virtuous character. This fact, however, became apparent only after their message gained acceptance within their community and it cannot be regarded as a viable verification of the claim of a prophet to those he calls upon. Al-Aš‘arī (d. 324/935), for instance, is said to have accepted a number of indications that allow humans to distinguish a prophet from ordinary people. He does not mention the claim based on the impeccable moral conduct of prophets. In fact, he stresses that in order to distinguish a true prophet from other people who are close to God (awliyā'), but who have no message to reveal, one should put oneÕs trust only in the occurrence of true prophetic miracles.

My aim here is to present an editio princeps of a newly discovered Arabic translation of a very important passage from Plato's Republic (Book VI, 506d3–509b10) found in the work entitled Kitāb fī Masā'il al-umūr al-ilāhiyya (hereafter Masā'il), penned by the somewhat obscure Neoplatonist Abū Hāmid al-Isfizārī (fl. mid-fourth / tenth c.). While an edition of al-Isfizārī's work has been published by Daniel Gimaret, the manuscript he used (Ragıp Paşa 1463) lacked the literal translation of the Republic passage. The one other known exemplar of the work, MS Zāhiriyya 4871, dated slightly later than the first, appears to be closer to the author's original unedited version; it contains the Republic passage. I am currently preparing a new edition of the work on the basis of the Zāhiriyya manuscript, but it seemed worthwhile to bring the Republic passage to immediate attention. I do not attempt here a thorough evaluation of al-Isfizārī's philosophy as presented in the Masā'il; this can be done successfully only upon completion of the edition. However, to place the work in its proper context, I do provide a brief overview of the transmission of Plato's Republic in Arabic; a discussion of new information on al-Isfizārī's Nachlass, and a description of the two exemplars of his Masā'il. The edited text of the passage from the Republic is accompanied by a provisional translation.

Suscités par la reprise massive de la recherche en astronomie au IXe siècle dans le monde islamique et essentiellement à Bagdad, laquelle nécessite des outils mathématiques nouveaux, une floraison de traités, tant astronomiques que mathématiques, voit le jour à cette époque. D'entre les traités mathématiques, un certain nombre est consacré à la ‘‘figure secteur” (al-shakl al-qattā‘), c’est-à-dire au théorème dit ‘‘de Ménélaüs” sur la sphère, lequel généralise le théorème dit ‘‘de Ménélaüs” dans le plan. Ce théorème de Ménélaüs sur la sphère, ou règle des six quantités, est, en l’absence du théorème des sinus sur la sphère, lequel ne date que de la deuxième moitié du Xe siècle, le principal outil de l'astronomie sphérique. Le traité de Thābit ibn Qurra (mort en 901) sur La figure secteur est le premier de ces traités consacrés au théorème de Ménélaüs, tant dans le plan que sur la sphère, à nous être parvenu; point de départ de tout un courant, il influencera profondément le développement ultérieur de la géométrie sphérique. Ce traité, qui est en fait une épître adressée à un correspondant malheureusement anonyme, présente en outre l'intérêt de montrer que, dans le milieu scientifique de cette époque à Bagdad, beaucoup s'intéressaient à ce théorème, essayaient d'en énoncer d'autres cas de figure et de compléter la démonstration qu'en donne Ptolémée dans l'Almageste.