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THEMISTIUS ° (317–c. 388 c.e.), statesman, rhetorician, and philosopher, known to medieval Jewish philosophers as a major interpreter of Aristotle; the author of commentaries which Maimonides recommends highly (see Maimonides' letter to Samuel ibn Tibbon, in S. Pines' introduction to his translation of The Guide of the Perplexed (1963), lix).

Themistius lived in Constantinople most of his life. A pagan, he held the office of senator and even prefect in the new Christian capital, and celebrated its emperors in several panegyrics. The pliant nature of Themistius' personality is also evident in his philosophical writings, in which he shows familiarity with the various currents of Greek philosophy and, in the tradition of late Greek thought, he believes Plato and Aristotle to be in substantial agreement.

Only two of Themistius' commentaries were translated into Hebrew (from earlier Arabic translation): his paraphrase of Aristotle's De caelo by Zerahiah b. Isaac *Gracian, in 1284; and his paraphrase of Book 12 of the Metaphysics by Moses ibn *Tibbon, in 1255 (both edited by S. Landauer, Commentaria in Aristotelem Graeca, 4 (1902), 1–167; 5 (1903), 1–35). Themistius' other commentaries, to the Prior and Posterior Analytics, the Physics, and De anima, were known either through Arabic translations or through secondary sources. He is often quoted by other late Hellenistic writers, notably John Philoponus, and by Islamic philosophers, particularly *Averroes. It is through supercommentaries to Averroes' writings that Themistius' views often find expression in the works of such late medieval Jewish figures as Levi b. Gershom and Moses of Narbonne.

Themistius' own contribution to Peripatetic philosophy lies in the interpretation, not completely consistent, which he gave to Aristotle's doctrine of the *intellect. He considered the "potential intellect" of Aristotle to be an independent, separate substance, though closely related, as matter is to form, to the similarly separate "agent intellect." He saw the intellect's bridge to corporeal forms and to man as accomplished through a "common," "passive intellect," neither separate nor immortal. Averroes was later to build upon this notion of an independent political intellect, identifying its substance completely with the universal Agent Intellect.


Pauly-Wissowa, 2nd series, vol. 5 (1934), s.v.Themistes; Steinschneider, Uebersetzungen, 125, 176; F.E. Peters, Aristoteles Arabus (1968), 16, 18, 34, 36, 42, 52; O. Hamelin, La théorie de l'intellect (1953), 38–43, 58–72.

[Alfred L. Ivry]