Ammonius was a Greek philosopher, surnamed Sacca ("sack-carrier"), founder of the neo-Platonic School, said to have been in his earlier days a porter in Alexandria. His parents were Christian, but he himself is said by Plotinus to have abandoned his earlier religion; although both Eusebius and St Jerome deny his apostasy. Ammonius opened a school of philosophy in Alexandria, and sought to harmonize, through a comprehensive eclecticism, the philosophies of Aristotle and Plato. He seems also to have added elements of oriental speculation; but it is doubtful how far neo-Platonism represents his own position. His most distinguished pupils were Origen and Plotinus. Ammonius Saccus died at Alexandria, 243 AD, at the age of more than 80. He left no writings behind him.
Ammonius was also the name of a Peripatetic philosopher of the 1st century, the instructor of Plutarch; of a Christian philosopher of the third century, who wrote a "Harmony of the Gospels;" of a philosopher of the fifth century, a disciple of Proclus, who left important commentaries on Aristotle; and of an Alexandrian grammarian of the fourth century.