Now Euxenus realized that he was attached to a lofty ideal, and asked him at what point he would begin it. Apollonius answered: "At the point at whic… - Philostratus

Apollonius … explained his motive in practicing wisdom, declaring that the sole use he had made of it was to gain knowledge of the gods and an understanding of human affairs, for that the difficulty of knowing another man exceeded that of knowing oneself.

Apollonius accordingly paused for a minute and then, fixing his eyes, as it were, on the discourse he had heard, he spoke as follows: "… I am not come here to ask your advice about how to live, insomuch as I long ago made choice of the life which seemed best to myself … For I discerned a certain sublimity in the discipline of Pythagoras, and how a certain secret wisdom enabled him to know, not only who he was himself, but also who he had been; and I saw that he approached the altars in purity, and suffered not his belly to be polluted by partaking of the flesh of animals and that he kept his body pure of all garments woven of dead animal refuse; and that he was the first of mankind to restrain his tongue, inventing a discipline of silence … I also saw that his philosophical system was in other respects oracular and true. So I ran to embrace his teachings …"

Apollonius then asked him [Iarchas] whether they knew themselves also, thinking that he, like the Greeks, would regard self-knowledge as a difficult matter. But the other, contrary to Apollonius' expectations, corrected him and said: "We know everything, just because we begin by knowing ourselves; for no one of us would be admitted to this philosophy unless he first knew himself." And Apollonius remembered what he had heard Phraotes say, and how he who would become a philosopher must examine himself before he undertakes the task; and he therefore acquiesced in this answer, for he was convinced of its truth in his own case also.