Ammianus Marcellinus Res Gestae 21.14.5

[5] Likewise from the immortal poems of Homer ¹ we are given to understand that it was not the gods of heaven that spoke with brave men, and stood by them or aided them as they fought, but that guardian spirits attended them; and through reliance upon their special support, it is said, that Pythagoras, Socrates, and Numa Pompilius ² became famous; also the earlier Scipio, ³ and (as some believe) Marius and Octavianus, who first had the title of Augustus conferred upon him, and Hermes Trismegistus, ⁴ Apollonius of Tyana, ⁵ and Plotinus, ⁶ who ventured to discourse on this mystic theme, and to present a profound discussion of the question by what elements these spirits are linked with men’s souls, and taking them to their bosoms, as it were, protect them (as long as possible) and give them higher instruction, if they perceive that they are pure and kept from the pollution of sin through association with an immaculate body.