THEIA (“Themistius, Heavens and Elements. Interpretations of Aristotle’s Cosmology Across the Ages”) is a project on the paraphrase of Aristotle’s De Caelo by the 4th century rhetor and philosopher Themistius. It will be argued in what follows that this paraphrase is important and has not received the attention it deserves. The history of Aristotelianism has not yet finished to provide materials for new insights, as shown by the recent 600 pages volume Aristotle Re-Interpreted edited by R. Sorabji. Yet, comparatively little attention has been paid to Themistius. This lacuna, relevant in itself, is even more regrettable in consideration of the fact that his fame as an Aristotelian exegete was great in the Latin Middle Ages and Renaissance. Some studies have been devoted to Themistius the rhetor, while his philosophical production has been addressed only selectively. Themistius’ interpretation of the De Anima has attracted scholarly attention, but his understanding of Aristotle’s cosmology – in the broad sense of the doctrine of the divine world (God and heavens) and of the generable/corruptible world (the sublunar realm) – is poorly studied, with the exception of a pioneering article by S. Pines.4 Today, the brand-new critical edition of
Themistius’ paraphrase of Metaphysics XII5 provides a solid foundation for the study of the role of this work in shaping the metaphysical landscape of Medieval Arabic and Hebrew philosophical theology. THEIA aims to complete this picture with Themistius’ cosmology, that is contained chiefly in his Paraphrase of Aristotle’s De Caelo (henceforth PDC).6 The importance of PDC in the history of Aristotelianism is beyond doubt, as it is the first complete exegesis of the De Caelo that has come down to us: Alexander of Aphrodisias’ commentary is lost, though attested fragmentarily by later authors (including Themistius himself).7 Adequate study of PDC has been hampered by the fact that the original Greek text is lost: we can read PDC only in a medieval Hebrew translation of the lost Arabic version, and in a Hebrew-into-Latin version produced in the Renaissance. Both texts, the Hebrew and the Latin, are edited,8 but the Latin is obviously derivative; in addition, as detailed below, the Hebrew text
requires a new critical edition. THEIA sets for itself the task to edit, translate into English, and comment upon the Hebrew text, namely the earliest version of PDC that is extant. Once the task accomplished, this will allow the
scholars in the field to get a more complete picture of 4th cent. Aristotelianism, be it through the lens of a medieval
Hebrew translation. The multi-layered history of PDC is also a case in point for reconstructing the transformations
undergone by Aristotle’s cosmology during the ages because of the hidden assumptions of its readers and
interpreters, from its enculturation in the Aristotelian circle of the 10th cent. Baghdad, when it was translated into
Arabic, to the Jewish learned community of the 13th cent. Rome. The reception of PDC, that will form part and
parcel of my commentary, sheds light on the interdisciplinary aspect of THEIA. Not only this project is
interdisciplinary as it combines history of philosophy and philology, but also as it contributes to a more complete
picture of the transmission of the Aristotelian cosmology across the ages, languages and cultures of the
Mediterranean area in pre-modern times. To this, another reason of interest should be added, that concerns the text
of Aristotle. The Hebrew version allows the scholar conversant with Themistius’ exegetical habits to reconstruct
some passages in the Greek original and to single out the Aristotelian lemmata of the De Caelo, interspersed in
Themistius’ wording. The retroversion of these lemmata into Greek will provide the philologist with an extremely
important piece of documentation: parts of the text of Aristotle’s De Caelo as it was read in the 4th century, i.e. five
centuries before the most ancient manuscrupt of this work.9 In this sense, THEIA can be considered an