Ammonius Hermiae

Ammonius Hermiae was a prominent Greek Neoplatonist philosopher active in Alexandria during the late fifth and early sixth centuries AD. Born into a distinguished philosophical family—his father was Hermias and his mother Aedesia—he was also the brother of the philosopher Heliodorus of Alexandria and the grandson of Syrianus, head of the Athenian Neoplatonic school. Ammonius became one of the most influential teachers of Late Antiquity, shaping the transmission of Platonism and Aristotelianism for subsequent generations.

Background and Intellectual Lineage

Raised in Alexandria after the early death of his father, Ammonius and his brother were taken by their mother to Athens when they reached adulthood. There they studied under Proclus, one of the leading Neoplatonists of the age. This training integrated them into a philosophical lineage that sought to harmonise Plato and Aristotle, a project that Ammonius would later continue within the Alexandrian school.
By the 470s, Ammonius had obtained a public academic chair in Alexandria. This position placed him at the centre of philosophical teaching in the eastern Roman Empire and allowed him to develop a long and influential career during a period in which pagan intellectual life faced increasing pressures from Christian authorities.

Teaching and Students

Ammonius taught a wide range of subjects, including Plato, Aristotle, Porphyry, Greek geometry, and ancient astronomy. His classes attracted numerous students, many of whom became prominent philosophers or scholars in their own right. These included:

• Damascius, later head of the Athenian school
• Olympiodorus of Thebes, an important source for his teachings
• John Philoponus, a major commentator and later critic of Aristotelian physics
• Simplicius of Cilicia, one of the last great ancient commentators
• Asclepius of Tralles, who preserved detailed lecture notes
• Gessius of Petra, physician
• Zacharias Rhetor, future bishop and church historian

Their writings constitute an important repository of Ammonius’ lectures, often quoted or paraphrased in commentaries that circulated widely across the late antique and medieval worlds.

Philosophical Context and Religious Pressures

During the late fifth century, as Christianisation intensified within the Roman Empire, pagan philosophical schools came under scrutiny. According to Damascius, the Alexandrian school was investigated by imperial authorities during a wave of anti-pagan measures in the 480s. Ammonius reached an agreement with Peter III, Patriarch of Alexandria, voluntarily restricting aspects of his teaching in exchange for the right to continue lecturing. Some contemporaries, notably Damascius, regarded this compromise critically, though they continued to respect his scholarly expertise. Despite these tensions, Ammonius remained an active teacher until at least 515, as confirmed by Olympiodorus.

Writings and Scholarly Contributions

Although ancient sources describe Ammonius as a prolific writer, only a limited number of works have survived in complete form. His extant and attributed writings include:

• Commentary on Aristotle’s De Interpretatione: his only fully preserved work, influential in medieval discussions of language, logic, and divine foreknowledge.
• Commentary on Porphyry’s Isagoge: sometimes attributed to him, though the text is corrupted and contains later additions.
• Treatise on the Astrolabe: evidence of his expertise in Greek astronomy, preserved in the Catalogus Codicum Astrologorum Graecorum.

A substantial body of material survives indirectly through student notes and commentaries:

• On Aristotle’s Categories (anonymous)
• On Aristotle’s Prior Analytics I (anonymous)
• On Aristotle’s Metaphysics 1–7 (by Asclepius of Tralles)
• On Nicomachus’ Introduction to Arithmetic (Asclepius)
• On Aristotle’s Prior and Posterior Analytics (John Philoponus)
• On Aristotle’s On Generation and Corruption (Philoponus)
• On Aristotle’s On the Soul (Philoponus)

A short Life of Aristotle, transmitted in Greek manuscripts and traditionally ascribed to Ammonius, is more plausibly attributed to his student Philoponus.
Ammonius’ surviving philosophical work shows a strong commitment to harmonising Plato and Aristotle. His discussion of divine foreknowledge in De Interpretatione argues that divine knowledge does not abolish contingency, drawing on earlier Neoplatonic ideas such as Iamblichus’ view of knowledge as the activity of the knower in relation to the known.

Influence and Legacy

Ammonius Hermiae was celebrated by later authors as a master interpreter of Aristotle. Damascius, despite criticising his concessions to Christian power, famously described him as “the greatest commentator who ever lived”. His synthesis of Aristotelian logic with Neoplatonic metaphysics laid the foundation for the Alexandrian style of commentary, which shaped philosophical instruction well into the Byzantine, Islamic, and medieval Latin traditions.
His students carried his teachings across the Mediterranean intellectual world, ensuring that Ammonius’ influence extended far beyond his lifetime. Through the works of Simplicius and Philoponus in particular, his interpretations became integral to subsequent philosophical debates in late antiquity and the Middle Ages.