Among the phenomena examined in the Meteorologica, some, although they are sublunar, are too distant to be accessible to direct study. To remedy this situation, it was necessary to develop procedures and methods which could allow observation, and above all the geometrical control of observations. The eventual result of this research was to detach the phenomenon under consideration from meteorology, and to insert it within optics or astronomy. Abū Sahl al-Qūhī (second half of the tenth century), composed a treatise on shooting stars in which he carries out such an insertion. In a second treatise, he deals with another type of observation, intended to measure maritime, terrestrial, and celestial surfaces. Here, the author studies al-Qūhī's contribution and gives the editio princeps of these two treatises, as well as their translation.

The essence of the theory of minima naturalia is the contention that a physical body is not infinitely divisible qua that specific body. A drop of water cannot be divided again and again and still maintain its “wateriness”. There are several statements in Aristotle's Physics which suggest such an interpretation, and the theory of minima naturalia is commonly considered to have originated in the thirteenth century as an interpretation of these statements. The present paper is a preliminary presentation of the role of Ibn Rushd in the evolution of the theory, hitherto neglected. His theory developed not only as an elaboration on the “suitable” statements of Aristotle, but mainly as an attempt to solve the difficulties raised by Aristotle's thesis (developed in Physics VI and VII) that body and motion are continuous, infinitely divisible entities and are associated qua such. According to Ibn Rushd's interpretation, body and motion are associated not qua being continuous but qua having indivisible minimal parts. It seems that Epicurus' and Ibn Rushd's theories of minima developed as responses to Physics VI and offer modifications of classical atomism and of classical Aristotelianism (respectively), which to a certain extent reduce the gap between these two systems.

Among the phenomena examined in the Meteorologica, some, although they are sublunar, are too distant to be accessible to direct study. To remedy this situation, it was necessary to develop procedures and methods which could allow observation, and above all the geometrical control of observations. The eventual result of this research was to detach the phenomenon under consideration from meteorology, and to insert it within optics or astronomy. Abū Sahl al-Qūhī (second half of the tenth century), composed a treatise on shooting stars in which he carries out such an insertion. In a second treatise, he deals with another type of observation, intended to measure maritime, terrestrial, and celestial surfaces. Here, the author studies al-Qūhī's contribution and gives the editio princeps of these two treatises, as well as their translation.

That the medieval Latin version of Ibn al-Haytham's Kitāb al-Manā[zdotu]ir was translated into Italian in the fourteenth century has been known for well over a century. Recent studies have shown that this translation, which is contained in Vat. Lat. 4595, was instrumental in the composition of Lorenzo Ghiberti's Commentario terzo on art. Some eight years ago, the author of the present article tentatively identified the actual manuscript-source of that translation as MS Royal 12.G.7, which is currently held in the British Library. This study establishes beyond reasonable doubt that his tentative identification was correct: MS Royal 12.G.7 is indeed the Latin source for the Italian translation in Vat. Lat. 4595.

Avicenna refers on a number of occasions in his Book of the Syllogism to “the eminent later scholar” (al-fā[ddotu]il min al-muta'a[hbrevu][hbrevu]irī). At least three recent studies have argued or assumed that this eminent later scholar is Alexander of Aphrodisias. It is argued in this article that Avicenna is in fact referring to Alfarabi. This has consequences for reconstructing the lost first part of Alfarabi's Great Commentary on the Prior Analytics, for highlighting certain aspects of Alfarabi's logical doctrines, and for understanding more about the relation between Avicenna and Alfarabi in matters logical.

The only traces which remain of Abū Sahl al-Qūhī's work on centers of gravity are the correspondence he maintained with Abū Is[hdotu]āq al-[Sdotu]ābi', and the first chapter of the Kitāb Mīzān al-[hdotu]ikma, which 'Abd al-Ra[hdotu]mān al-Khāzinī attributes to al-Qūhī and to Ibn al-Haytham, without distinguishing between their respective contributions. The author of the present article attempts to confront the texts and to analyse all the testimonies which have come down to us on this subject, which are susceptible of shedding light upon al-Qūhī's contribution and the importance of his work on centers of gravity.

A part of chapter 1, Book II of the Physics of the šif¯' is dedicated to the aristotelian definition of motion (Physics III, 1, 201a10-11). The developments to which the treatment of this question gives rise are distinctive of the Avicennian style in his Physics. By assuming the notion of double entelechy, Avicenna is following the most classical exegetical tradition. However, by setting a correspondence between the double entelechy and the double notion of motion: 1) motion as an intermediary state, which can be ascribed to a moving object at any instant of its trajectory, and 2) motion as a traversal of a given distance, which cannot be ascribed to the moving object, but at the end-point of its trajectory, Avicenna gives a new content to a lieu commun of the exegetical tradition.

The aim of this paper is to present the modes of action of venom as construed by Abū 'Uthmān 'Amr ibn Ba[hdotu]r al-Jā[hdotu]i[zdotu] (780-868) in his Kitāb al-[Hdotu]ayawān (The Book of Animals). The toxicological information presented by Jā[hdotu]i[zdotu] is a synthesis of data available in his time, but Jā[hdotu]i[zdotu] complemented these early conceptions by his personal theoretical views. Jā[hdotu]i[zdotu]'s fundamental idea is that venoms act through their specific natures; this idea in a way is reminiscent of present-day theory of enzymes.

The autobiography witnesses a significant evolution in Avicenna's approach to Aristotle's Metaphysics during the years of his education. It clearly shows that, at a certain point of his philosophical training, Avicenna faced the entire text of the Metaphysics, was puzzled by its extent and complexity, and found in a treatise by al-Fārābī a guide for its understanding. But, albeit less perspicuously, the autobiography also suggests that this was not Avicenna's first encounter with the Metaphysics. Avicenna dealt with Aristotle's work in a previous stage of his studies as well. Then, however, he did not read the Metaphysics in its entirety, but, rather, focused only on its essential parts and some commentaries thereupon. The parts of the Metaphysics that Avicenna read in this earlier stage were books Alpha Elatton and Lambda, as constituting the natural theology of Aristotle's work. He neglected, on the contrary, the books corresponding to its ontological part. The special attention to Alpha Elatton and Lambda and the close connection between these two books in a theological context were peculiar traits of al-Kindī's approach to Aristotle's Metaphysics. Therefore, the evolving approach to Aristotle's Metaphysics that Avicenna's autobiography witnesses can properly be described as a passage from the Kindian to the Farabian way of interpretation.

Abraham ibn Ezra's (ca 1089-ca 1167) scientific corpus represented an exceptional case: instead of the common Latin model embodied by the scholar coming from the Christian North to the Iberian Peninsula to initiate a translation enterprise, we have in Ibn Ezra the contrary case of an intellectual imbued with the Arabic culture, who abandons al-Andalus, roams around the Christian countries and delivers in his wandering through Italy, France and England, the scientific and cultural cargo that he amassed during his youth in al-Andalus. The main purpose of this article is to provide a picture of Ibn Ezra's scientific corpus as comprehensive and detailed as possible given the present state of research. The paper will fall into two main parts: (a) Ibn Ezra's scientific work will be broken up into three main genres: (1) Mathematics, Astronomy, Scientific Instruments and Tools; (2) The astrological encyclopaedia; (3) Translations from Arabic into Hebrew. (b) In the second part, Ibn Ezra's scientific corpus will be reassembled as a whole in order to provide a global characterization, trying to point out its general organization and shape, and to indicate its main aims and special traits revealing Ibn Ezra personal contribution.

Na[sdotu]īr al-Dīn al-[Tdotu]ūsī, Memoir on Astronomy (al-Tadhkira fī ‘ilm al-hay’a, Edited with Introduction, Translation and Commentary by F.J. Ragep, 2 vols., XV + 656 + XV pp., figs., index. New York - Berlin - Heidelberg..., Springer Verlag, 1993 (Sources in the History of Mathematics and Physical Sciences, 12).

[Sdotu]adr al-Sharī‘a. An Islamic Response to Greek Astronomy: Kitāb Ta‘dīl Hay’at al-Aflāk of [sdotu]adr al-Sharīa, Edited with Translation and Commentary by Ahmad S. Dallal, X + 461 pp., figs., index. Leiden - New York - Köln, E.J. Brill, 1995 (Islamic Philosophy, Theology & Science, Texts and Studies, vol. 23).