Ammonius Saccas (; Greek: Ἀμμώνιος Σακκᾶς; fl. 3rd century AD) was a Greek philosopher from Alexandria who was often referred to as one of the founders of Neoplatonism. He is mainly known as the teacher of Plotinus, whom he taught for eleven years from 232 to 243. He was undoubtedly the biggest influence on Plotinus in his development of Neoplatonism, although little is known about his own philosophical views. Later Christian writers stated that Ammonius was a Christian, but it is now generally assumed that there was a different Ammonius of Alexandria who wrote biblical texts.
Not much is known about the life of Ammonius Saccas.
His cognomen "Sakkas" has been interpreted to indicate that he was a porter in his youth. This seems to be a misreading of "Sakkas" for "sakkophoros" (porter) which is grammatically incorrect. However Erich Seeberg argued that the cognomen refers to the "Śākyas" of India, the ruling clan to which Gautama Buddha also belonged. The "Śākyas" (related to Iranian Saka, Scythians and Indo-Scythians) were known in antiquity. The cognomen "Sakkas" therefore referred to India  as a marker of ethnic identity. This is, according to this interpretation, supported by the fact that Ammianus Marcellinus refers to him as "Saccas Ammonius", thus as the "Sacian Ammonius", which makes any reading as denoting "sakkos" impossible. This interpretation of the name, which has subsequently been contested, would corroborate Porphyry's report that Plotinus, Ammonius' foremost student, acquired his high esteem for Indian philosophy and his eager desire to travel to India from Ammonius.
The interpretation that "Saccas" denotes ethnic northern Indian origin, rather than alluding to Gautama Buddha, supports the possibility that Ammonius may have been raised a Christian, who reverted to paganism, as reported by Eusebius, drawing on Porphyry's Contra Christianos. In this case Ammonius may have been a second-generation Indian who remained in contact with the philosophy of his ancestral country. The intensity of commerce of goods and ideas between Alexandria and India makes this a wholly possible option.
The link to India however is not only consistent with Plotinus' passion for India, but also helps to explain the often noted substantial agreements and shared ideas between Vedanta and Neoplatonism which are increasingly attributed to direct Indian influence.
Most details of his life come from the fragments left from Porphyry's writings. The most famous pupil of Ammonius Saccas was Plotinus who studied under Ammonius for eleven years. According to Porphyry, in 232, at the age of 28, Plotinus went to Alexandria to study philosophy:
In his twenty-eighth year he [Plotinus] felt the impulse to study philosophy and was recommended to the teachers in Alexandria who then had the highest reputation; but he came away from their lectures so depressed and full of sadness that he told his trouble to one of his friends. The friend, understanding the desire of his heart, sent him to Ammonius, whom he had not so far tried. He went and heard him, and said to his friend, "This is the man I was looking for." From that day he stayed continually with Ammonius and acquired so complete a training in philosophy that he became eager to make acquaintance with the Persian philosophical discipline and that prevailing among the Indians.
According to Porphyry, the parents of Ammonius were Christians, but upon learning Greek philosophy, Ammonius rejected his parents' religion for paganism. This conversion is contested by the Christian writers Jerome and Eusebius, who state that Ammonius remained a Christian throughout his lifetime:
[Porphyry] plainly utters a falsehood (for what will not an opposer of Christians do?) when he says that ... Ammonius fell from a life of piety into heathen customs. ... Ammonius held the divine philosophy unshaken and unadulterated to the end of his life. His works yet extant show this, as he is celebrated among many for the writings which he has left.
However, we are told by Longinus that Ammonius wrote nothing, and if Ammonius was the principal influence on Plotinus, then it is unlikely that Ammonius would have been a Christian. One way to explain much of the confusion concerning Ammonius is to assume that there were two people called Ammonius: Ammonius Saccas who taught Plotinus, and an Ammonius the Christian who wrote biblical texts. Another explanation might be that there was only one Ammonius but that Origen, who found the Neo-Platonist views of his teacher essential to his own beliefs about the essential nature of Christianity, chose to suppress Ammonius' choice of Paganism over Christianity. The insistence of Eusebius, Origen's pupil, and Jerome, all of whom were recognized Fathers of the Christian Church, that Ammonius Saccas had not rejected his Christian roots would be easier for Christians to accept than the assertion of Prophyry, who was a Pagan, that Ammonius had chosen Paganism over Christianity.
To add to the confusion, it seems that Ammonius had two pupils called Origen: Origen the Christian, and Origen the Pagan. It is quite possible that Ammonius Saccas taught both Origens. And since there were two Origens who were accepted as contemporaries it was easy for later Christians to accept that there were two individuals named Ammonius, one a Christian and one a Pagan. Among Ammonius' other pupils there were Herennius and Cassius Longinus.
He was the first who had a godly zeal for the truth in philosophy and despised the views of the majority, which were a disgrace to philosophy. He apprehended well the views of each of the two philosophers [Plato and Aristotle] and brought them under one and the same nous and transmitted philosophy without conflicts to all of his disciples, and especially to the best of those acquainted with him, Plotinus, Origen, and their successors.
Little is known about Ammonius's role in the development of Neoplatonism. Porphyry seems to suggest that Ammonius was instrumental in helping Plotinus think about philosophy in new ways:
But he [Plotinus] did not just speak straight out of these books but took a distinctive personal line in his consideration, and brought the mind of Ammonius' to bear on the investigation in hand.
Two of Ammonius's students - Origen the Pagan, and Longinus - seem to have held philosophical positions which were closer to Middle Platonism than Neoplatonism, which perhaps suggests that Ammonius's doctrines were also closer to those of Middle Platonism than the Neoplatonism developed by Plotinus (see the Enneads), but Plotinus does not seem to have thought that he was departing in any significant way from that of his master.
- , (Henry WAce, ed.), John Murrary & Co., London, 1911Dictionary of Early Christian BiographyMozley, J.R., "Ammonius Saccas",
- Seeberg, Erich, "Ammonius Sakas", in: Zeitschrift für Kirchengeschichte, vol. LX, 1941, pp. 136 - 170
- see art.: "India" in: Pauly-Wissova, col. 1924
- Benz, Ernst, "Indische Einflüsse auf die frühchristliche Theologie" in: Abhandlungen der Geistes- und Sozialwissenschaftlichen Klasse, Jahrgang 1951, no. 3, Akademie der Wissenschaften und der Literatur Mainz, pp. 1 - 34, pp. 30ff.
- Clifford Hindley: Ammonios Sakkas. His Name and Origin. In: Zeitschrift für Kirchengeschichte 75, 1964, pp. 332–336.
- ibidem, cf. Porphyry's Vita Plotini, chapt. 3
- Eusebius, Historia eccl. VI, 9
- Harris, R. Baine (ed.), Neoplatonism and Indian Thought, Norfolk Va., 1982: The International Society for Neoplatonic Studies
- Porphyry, Life of Plotinus, from Reale, G., (1990), A History of Ancient Philosophy IV: The Schools of the Imperial Age. Page 298. SUNY Press.
- Eusebius, History of the Church, vi, 19.
- Longinus, quoted by Porphyry, Life of Plotinus, xx.
- Hierocles in Photius, Bibl. cod. 214, 251.
- Hierocles, in Photius, Bibl. cod. 251. from Karamanolis, G., (2006), Plato and Aristotle in Agreement?: Platonists on Aristotle from Antiochus to Porphyry, Page 193. Oxford University Press.
- Nemesius, On the Nature of Man, ii
- Armstrong, A., (1967), The Cambridge History of Later Greek and Early Medieval Philosophy, Cambridge University Press, pp. 196–200.
- Karamanolis, G., (2006), Plato and Aristotle in Agreement?: Platonists on Aristotle from Antiochus to Porphyry, Oxford University Press, pp. 191–215.
- Reale, G., (1990), A History of Ancient Philosophy IV: The Schools of the Imperial Age, SUNY Press, pp. 297–303.
- Porphyry, Against the Christians (2004). Fragments.
- The Reaction to the Bible in Paganism
- Origen - Internet Encyclopedia of Philosophy