Category: Persons

Ammonius, son of Hermias

Neoplatonist philosopher, who held the public chair of philosophy in Alexandria during the last decades of the 5th and the first decades of the 6th century AD. His exegetical output, such as it was recorded and published mostly by his students, was very large. His exegetical method and philosophical interpretation, which sought to highlight the theological character of Aristotle's physics and consolidate the agreement of the latter with Plato, became dominant at the end of Late Antiquity.

Life and work

Ammonius was the son of the philosopher Hermias, who taught philosophy at the public chair of Alexandria (see The Neoplatonic school of Alexandria), and Aedesia, a relative of the Platonic successor Syrianus (see The Neoplatonic school of Athens). He was born around 440 in Alexandria and subsequently, after Hermias’ death and with the encouragement of his mother, he studied under the Platonic successor Proclus in Athens (his father having studied likewise under Syrianus), before returning to Alexandria to take up the public chair of philosophy. The Platonic successor Damascius, who studied for some time under Ammonius and his brother Heliodorus, emphasizes Ammonius’ intelligence and love of learning and reports that he surpassed his contemporaries in knowledge of both philosophy and mathematics. It is reported that Ammonius also taught Damascius astronomy, while Simplicius, who was a student of both philosophers, mentions the use of the astrolabe which Ammonius once made in his presence in Alexandria. The year of his death can reasonably be placed before 517, the year in which Ammonius’ disciple John Philoponus gave in Alexandria his public lectures on the fourth book of Aristotle's Physics, in which he criticizes his teacher’s interpretation in a manner which we can hardly imagine that he would dare use, had Ammonius been still alive.

Ammonius’ surviving work relates almost exclusively to Aristotle. He himself published only his Commentary on Aristotle’s On interpretation, but many of his lectures were published by his disciples (σχόλια ἀπὸ φωνῆς or σχολικαὶ ἀποσημειώσεις). Unnamed disciples of Ammonius published his Commentaries on Porphyry’s Isagoge, on Aristotle’s Categories and on part of the Prior Analytics, while his disciple Asclepius of Tralles published Ammonius’ Commentary on Aristotle’s Metaphysics. The Christian John Philoponus edited much of his teacher’s Aristotelian work, gradually distancing himself from his interpretation; Philoponus is mentioned as editor of Ammonius’ Commentaries on the Prior Analytics and on the Posterior Analytics, on the first two books of the Physics, on On generation and corruption, and on the first two books of On the soul.

Although Ammonius’ surviving exegetical work is related to Aristotle, it seems that Ammonius taught systematically the Platonic dialogues as well. Damascius is said to have attended Ammonius’ Platonic lectures, while the Commentary on the Metaphysics mentions his ἐξήγησις of the Theaetetus. Similarly, the Commentary on the Posterior Analytics makes reference to a Commentary by Ammonius on the Phaedo, while Olympiodorus, a descendant of Ammonius who later held the chair of philosophy in Alexandria, reports that he had attended Ammonius’ lectures on the Platonic Gorgias.

In order to solve theological interpretative problems, Ammonius also wrote μονόβιβλοι, which, although not preserved, are attested by Simplicius and Olympiodorus. With such a μονόβιβλος, Ammonius refuted the thesis of earlier Academic skeptics that Plato doubts the immortality of the soul in Phaedo 69d, while, by means of a likewise separate treatise, he undertook to show, chiefly against the Peripatetic commentator Alexander of Aphrodisias (2nd century AD), that the νοῦς according to Aristotle is not only the final cause of the universe, but also its efficient cause. It seems that both these μονόβιβλοι served the case of the agreement within Greek philosophical tradition and, in particular, the agreement of Aristotle with Plato, which Ammonius stressed systematically with his work.

Main features and aim of his exegesis

Ammonius tries to establish the overall agreement of the philosophy of Aristotle with the philosophy of Plato. Ιn this way, he expands Porphyry’s earlier view, which Syrianus and Proclus appear to have followed in Athens, that only a part of the philosophy of the Stagirite agrees with the Platonic work and is therefore useful for its comprehension. Arguing that, when Aristotle criticizes Plato, he does not address the philosopher himself but those who misinterpret the Platonic text, Ammonius circumvents the Stagirite’s frequent disagreement with his teacher. Philoponus disapproved of this interpretation of the Aristotelian critique, while Simplicius adopted and developed it further. Simplicius also borrows from Ammonius the theological reading of Aristotle’s physics, according to which the “first unmoved mover” is identified with the efficient cause of the universe (see primary sources 1). Finally, Ammonius is responsible for the distinction between theological physics, which corresponds to the physics of Plato’s Timaeus, and natural theology, which is expounded in Aristotle’s Metaphysics; this distinction exhibits once more the compatibility and complementarity of Ammonius’ approach to the two philosophers (see primary sources 2).

Ammonius is also the commentator who established the method of “double exegesis” (θεωρία καὶ λέξις) in the teaching practice, which was espoused by his students John Philoponus and Olympiodorus, as well as by the last generation of Alexandrian commentators (Stephen, Elias, David).


1) Simplicius, Commentary on Aristotle’s On the heavens, ed. J. L. Heiberg, in Commentaria in Aristotelem Graeca, vol. 7 (Berlin 1893) 271.13-21:

"Aristotle does not believe that God is only the final cause of the universe, which provoked Alexander’s aporia, but also the efficient cause. In this respect, instead of numerous other examples, a single phrase by Aristotle is sufficient: the one contained in this book, according to which neither God nor nature do (ποιεῖ) anything without purpose; also sufficient is the fact that he has shown that that is where the eternal movement of the ether comes from, though the ether has by itself finite power; sufficient altogether is also my own teacher Ammonius, who shows in his entire book exactly this, that Aristotle knows that God is not only the final but also the efficient cause of the universe."

2) John Philoponus, <Σχολικαὶ> ἀποσημειώσεις ἐκ τῶν συνουσιῶν Ἀμμωνίου τοῦ Ἑρμείου εἰς τὸ Περὶ φυσικῆς ἀκροάσεως τοῦ Ἀριστοτέλους…, ed. H. Vitelli, in Commentaria in Aristotelem Graeca, vol. 16 (Berlin 1887) 5.21-24:

"One can both do physics in a theological manner, like Plato in the Timaeus where he discusses the transcendental causes of natural things, and theology in a natural way, like Aristotle in the Metaphysics where he begins from the natural things in order to develop his teaching on the divine."

Author: Pantelis Golitsis
  • Golitsis, P, Les Commentaires de Simplicius et de Jean Philopon à la Physique d’Aristote. Tradition et innovation. Berlin, 2008.
  • Westerink, L. GSorabji, R. ed. . Aristotle Transformed. The Ancient Commentators and Their Influence. Ithaca, 1990.
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