Lysis, after having indicated the route by which Pythagoras conducted his disciples to virtue, goes on to teach them the use that this philosopher wished them to make of this celestial gift, once they had mastered it. Up to this point it is confined in the purgative part of the doctrine of his teacher; he now passes to the unitive part, that is to say, to that which has as object the uniting of man to the Divinity, by rendering him more and more like unto the model of all perfection and of all wisdom, which is God. The sole instrument capable of operating this union has been placed at his disposition by means of the good usage that he has made of his will: it is virtue which must serve him at present to attain truth. Now, Truth is the ultimate goal of perfection: there is nothing beyond it and nothing this side of it but error; light springs from it; it is the soul of God, according to Pythagoras,[480] and God himself, according to the legislator of the Indians.[481] The first precept that Pythagoras gave to his disciples on entering the course of perfection tended to turn their thoughts upon themselves, to bring them to interrogate their actions, their thoughts, their discourse, to question the motives, to reflect in short upon their exterior movements and seek thus to know themselves. Knowledge of self was the most important knowledge of all, that which must conduct them to all others. I will not weary my readers by adding anything to what I have already said pertaining to the importance of this knowledge, and the extreme value set upon it by the ancients. They know unquestionably that the morals of Socrates and the philosophy of Plato were only the development of it and that an inscription in the temple of Greece, that of Delphi, commended it, after that of the golden mean, as the very teaching of the God whom they worshipped there[482]: _Nothing in excess, and know Thyself_, contained in few words the doctrine of the sages, and presented for their meditation the principles upon which reposed virtue and wisdom which is its consequence. Nothing further was necessary to electrify the soul of Heraclitus and to develop the germs of genius, which until the moment when he read these two sentences were buried in a cold inertia.