Apropos of nothing:
Ammonius Saccas (175-c. 245) is regarded as a founder of neoplatonism. He is mainly known as the teacher of Plotinus (205-270), whom he taught from 232 to 243. He also taught Origen (c. 184–c. 253), although we cannot date the years with any certainty. The two students were a generation apart, so unlikely that they met, but not impossible!
Later Christian writers said Ammonius was a Christian, but were probably mixing him up with another Ammonius of Alexandria who wrote biblical texts.
Some say 'Saccas' derives from Śākyas, an ancient ruling clan of India, and that Ammonius was of Indian origin, a view both contested and supported by recent scholarship. Some scholars supporting Ammonius' Indian origins have also contended that this ancestry is consistent with the passion of his foremost student Plotinus for India – Plotinus travelled East in pursuit of further knowledge after leaving Alexandria, but not as far as India.
Swami Krishnanada says:
"Plotinus, the celebrated mystic, comes nearest in his views to the Vedanta philosophy, and is practically in full agreement with the Eastern sages, both in his theory and his methodology... To Plotinus, God or the Absolute is the All... above all contradictions and differences. It is the first causeless Cause, and the world emanates from It as an overflow of its Perfection... This is nothing short of the Advaita Vedanta of Shankara. Only the view that the world is an overflow of the Perfection of God is peculiar to Plotinus. For, to the Vedanta, there is no such overflow; there is, to it, only the Absolute, and the world is its appearance; not an emanation from or an overflow of its being."
Plotinus' disciple Porphyry records that Plotinus 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 – In Acts 17:21, Luke offers an aside: "Now all the Athenians, and strangers that were there, employed themselves in nothing else, but either in telling or in hearing some new thing." Luke's disparaging of Athens, always seeking after novelty, seems to have transferred to Alexandria, where some accused the city of being a hotbed of intellectual novelty-seeking and faddery. Whatever the case, Plotinus was deeply dissatisfied with what Alexandria had to offer. In his despair, a friend suggested he give it one last shot, and seek out Ammonius Saccas. He went, and said to his friend, "This is the man I was looking for."
From Ammonius he became eager to acquaint himself with Persian philosophical disciplines "and that prevailing among the Indians." (Porphyry) although, as I said, he never reached India.
Little is known about Ammonius' role in the development of Neoplatonism. He himself is categorised as a 'Middle Platonist' (these are categories determined much, much later by scholars highlighting the development of Plato's original models). Porphyry seems to suggest that Ammonius was instrumental in helping Plotinus think about philosophy in new ways.
To add to the confusion:
According to Porphyry, the parents of Ammonius were Christian, but he rejected their religion in favour of pure philosophy (which would have had its 'religious' dimension). This was contested by Jerome and Eusebius, but it appears they were confusing Ammonius Saccas with the Ammonius of Alexandria who wrote biblical texts.
It seems that Ammonius had two pupils called Origen: Origen the Christian, and Origen the Pagan. 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...
