These lines, which express the general outline of this last part, are remarkable, and one cannot conceive how Hierocles could have overlooked or neglected them. Although, it is true, they add nothing in the literal sense, they say much, however, in the figurative sense; they serve as proof of the division of this poem, which Hierocles himself has adopted without explanation. Lysis indicates quite strongly that he is about to pass on to a new teaching: he calls the attention of the disciple of Pythagoras to the new career which is opened before him, and to the means of traversing it and of attaining to the divine virtues which must crown it. This means is the knowledge of oneself, as I have said. This knowledge, so commended by the ancient sages, so exalted by them, which must open the avenues of all the others and deliver to them the key of the mysteries of nature and the doors of the Universe; this knowledge, I say, could not be exposed unveiled at the epoch when Pythagoras lived, on account of the secrets that it would of necessity betray. Likewise this philosopher had the habit of proclaiming it under the emblem of the sacred Tetrad or of the Quaternary. This is why Lysis, in invoking the name of his master, designates it on this occasion with the most striking characteristic of his doctrine. “I swear,” he said, “by the one who has revealed to our soul the knowledge of the Tetrad, that source of eternal Nature”: that is to say, I swear by the one who, teaching our soul to know itself, has put it in condition to know all nature of which it is the abridged image.