The problem of the Qibla was one of the central issues in the scientific culture of Medieval Islam, and to solve it properly, one needed mathematics and observation. The mathematics consisted of two parts: plane trigonometry (to construct the trigonometric tables) and spherical trigonometry (as the problem belongs to spherical astronomy). Observation and its instruments were needed to find the geographical coordinates of Mecca and the given location; these coordinates (latitude, longitude) will be the input data in the formulas of the Qibla. In his Almagest, Abū al-Wafāʾ produced a brilliant work to solve the problem. He worked on both mathematics and observation, and reached accurate and easy “modern” solutions. In plane trigonometry, he introduced the trigonometric functions with new definitions, proved the formulas for sines, approximated the sine of degree one, and thus constructed the tables of sines and tangents with high accuracy. In spherical trigonometry, he proved four new spherical theorems, including the tangent rule (which was based on the new definitions and this rule allowed him to work out the easiest solution, as will be shown). In observation, he described three instruments which he used over several years in Baghdad. This paper is a detailed technical and analytical description of Abū al-Wafāʾ's mathematical methods and the Qibla determinations, supplemented with many important original Arabic texts with translation and commentary.

Ibn Sīnā's celestial kinematics represents an important aspect of his cosmology but has up to now received little attention in the secondary literature. After a short overview of some key features of his cosmology, this article attempts to clarify the role played by the separate intellects, the celestial souls, and the celestial bodies in causing celestial motion. It challenges the common view that Ibn Sīnā adhered to the theory of ten separate intellects developed by al-Fārābī and attempts to reconstruct his astronomical-metaphysical model on the basis of his main philosophical works. In addition, the article addresses the thorny question of how motion is transmitted from the intellectual to the physical plane, and it sheds light on the place of physics, metaphysics, and astronomy in Ibn Sīnā's cosmological method.

The article examines the relation that Aquinas' theory of the beatific vision maintains with Averroes' noetics as presented in his Great Commentary on the De anima. Starting with his Commentary on the Sentences, in which the young Thomas Aquinas offers an explicit transposition of the philosophical intellection of separate substances into the Christian theological order, through to his later works where no mention of it is found, we will endeavour to present the exact nature of these borrowings and to evaluate their accuracy by questioning the conceptual coherence of Aquinas' gesture: could Aquinas base his conception of a vision of God by essence on a noetic construction which was originally part of a system judged both erroneous and contrary to faith? Can one concede theologically, concerning the relation between divine essence and intellect, what one refuses philosophically, concerning the relation between the separate intellect and the body? Although Aquinas and his followers, in the incipient quarrel, assert it to be so, we will indicate how the original paradoxical borrowing maintains something conceptually problematic at the heart of Aquinas' thinking.

The extant texts of the Arabic Plotinus contain material from Enneads IV-VI without, however, covering the Plotinian treatises in their entirety, nor preserving their traditional order – a circumstance which raises questions about scope and structure of the original Arabic Plotinus source. This article aims to contribute to the discussion by presenting newly discovered fragments of an Arabic translation of Ennead IV.6 (On sense-perception and memory), one of the ten treatises that are not represented in the Arabic Plotinus corpus as it is currently known. Section I of the article introduces the text within which the new fragments are found: Maqāla I of Kitāb al-Ḥiss wa-al-maḥsūs, the Arabic adaptation of Aristotle's Parva Naturalia. In Section II the Arabic fragments are presented in comparison with their Greek counterparts. Section III addresses the question whether these new fragments stem from the same original translation as the other fragments of the Arabic Plotinus. Section IV discusses the implications which the appearance of the new fragments may have for our views on the Arabic Plotinus as well as on the genesis of Kitāb al-Ḥiss wa-al-maḥsūs.

This paper seeks to draw attention to the existence of strong practical rationality in the work of Avempace, despite the primacy of theoretical reason, and of the search for an intelligible that is devoid of any link with the material and considered itself as the supreme end of human existence. The arguments used to defend the idea entail analysing the concept of “prudence” in Avempace, as well as that of “right thinking”, which is prominent in the determination of the way of life that philosophers must adopt in unjust cities. In addition, the elucidation of these aspects is a measure of the intellectual distance between Avempace and the mystics, both on the ethical-political and ontotheological levels.

Ḥunayn ibn Isḥāq's Arabic translation of Galen's commentary on the Hippocratic Epidemics is an invaluable source for our knowledge of Galenic medicine and its transmission history, not least because much of it is extant only in Arabic. Its importance for the Arabic medical tradition is amply attested in the later medical literature. It also tells us much about the methods and self-image of contemporary translators. Throughout the translation, we find remarks by Ḥunayn discussing the quality of his source text, his own interpretation and also his attempts to reconstruct problematic or damaged passages. Based on an edition of these notes, their analysis and comparison to similar texts and Galen's own thought on editing and interpreting difficult medical texts, this article aims to situate Ḥunayn's methods in the context of the Greek-Arabic translation movement. It argues that his approach differs in important respects from that of preceding Greek-Arabic and Greek-Syriac translators and that he was indebted to Galen not just as a physician, but also as a translator and exegete.

If anyone still raises doubts about the function of philology and the need for critical editions, this book should definitely put those doubts to rest. It shows that no history of philosophy is possible without intensive philological work with the original texts.

This article lists the medical works written by Ibn Bājja, overviews those that have come down to us and studies the super-commentary of Galen's commentary to Hippocrates' Aphorisms (Sharḥ fī al-Fuṣūl). This text shows a deep influence of al-Fārābī, namely in a conception of medical experience which stems from the latter's construal of experience (tajriba) as the inductive process described by Aristotle in Posterior Analytics which brings the premises of demonstration. On this basis, Ibn Bājja advocated for a less scholastic, more empiric medicine, and his claim was echoed by Ibn Rushd. There are some similarities between Ibn Bājja's text and Ibn Rushd's K. al-Kulliyyāt fī al-ṭibb which suggest that the latter had read Sharḥ fī al-Fuṣūl. This work gives moreover some evidence that human dissection could have been performed during Ibn Bājja's time.

Books belonging to adab literature present material about a variety of subjects, considered from various points of view, such as religious, scientific, historical, literary, etc. They contain knowledge and at the same time entertainment for educated people. Here we consider the content of two adab works, insofar as they discuss subjects from the scientific point of view: (an extract of) Faṣl al-Khiṭāb by al-Tīfāshī (d. 1253) and Mabāhij al-fikar wa-manāhij al-ʿibar by al-Waṭwāṭ (d. 1318).

Al-Tīfāshī's work discusses astronomical and meteorological subjects. The passages on astronomy give the usual Aristotelian cosmological picture of the world in a simplified version for non-specialists. The passages on meteorological subjects explain these phenomena in agreement with Aristotle's theory of the double exhalation, and it appears that they are based to a large extent on Ibn Sīnā's interpretation of this theory.

The book of al-Waṭwāṭ consists of four sections, which deal with the heaven, the earth, animals and plants respectively. One chapter of the first section deals with meteorological phenomena and presents a survey of the explanations current in his time, such as may be found in the works of al-Kindī and Ibn Sīnā.

One will probably not find new and original scientific ideas in the adab literature, but one gets an impression of how besides knowledge of Qurʾān, ḥadīth, poetry and literary prose scientific knowledge was a part of the education of a certain class of people, also of those whose special interest was not science. It also appears that the subjects of science were not restricted to those which were useful for religion and Muslim society. Science was an integrated activity in society, pursued for intellectual satisfaction and pleasure in knowledge, and most groups in that society held that there was nothing in it that would be incompatible with Islam as a religion. This would support the ‘appropriation thesis’ defended by Sabra, that science in medieval Islamic society was well assimilated and widely accepted, as opposed to the the ‘marginality thesis’ adopted by von Grünebaum, that science was a marginal activity, restricted to small elite circles and not rooted in society.

Dans l'horizon de l’étude de la philosophie naturelle d'Averroès, le nouveau travail de Ruth Glasner (RG) intitulé Averroes’ Physics: a Turning Point in Medieval Natural Philosophy occupera assurément une place de premier plan. Dans cet ouvrage, RG propose une étude analytique des trois commentaires d'Averroès à la Physique d'Aristote – l’Abrégé, le Commentaire Moyen et le Grand Commentaire. La force incontestable de son travail réside tout d'abord dans son approche double du texte d'Averroès, à la fois philologique et théorique. Tout au long de son analyse, ces deux aspects restent intimement liés et la mobilisation des instruments philologiques n'est jamais une fin en soi. Cette analyse a en effet pour but ultime de reconstruire le système du monde tel qu'Averroès le concevait. L'enjeu fondamental de cette étude est alors de supplanter la vision d'un Averroès interprète servile de la physique aristotélicienne et de présenter sa conception de la nature comme un système cohérent, organique et original.