As being is the source of not-being (§ 40), by identifying one's self with being one attains to all that is not-being, i.e. to all that exists. Instead, therefore, of aiming at acquiring knowledge, the wise man avoids it: instead of acting, he refuses to act. He "feeds his mind with a wise passiveness." (§ 16.) "_Not to act_ is the source of all power," is a thesis continually present to the mind of Lao (§§ 3, 23, 38,43,48, 63). The wise man is like water (§§ 8, 78), which seems weak and is strong; which yields, seeks the lowest place, which seems the softest thing and breaks the hardest thing. To be wise one must renounce wisdom, to be good one must renounce justice and humanity, to be learned one must renounce knowledge (§§ 19, 20, 45), and must have no desires (§§ 8, 22), must detach one's self from all things (§ 20) and be like a new-born babe. From everything proceeds its opposite, the easy from the difficult, the difficult from the easy, the long from the short, the high from the low, ignorance from knowledge, knowledge from ignorance, the first from the last, the last from the first. These antagonisms are mutually related by the hidden principle of the Tao (§§ 2, 27). Nothing is independent or capable of existing save through its opposite. The good man and bad man are equally necessary to each other (§ 27). To desire aright is not to desire (§ 64). The saint can do great things because he does not attempt to do them (§ 63). The unwarlike man conquers.[19] He who submits to others controls them. By this negation of all things we come into possession of all things (§ 68). _Not to act_ is, therefore, the secret of all power (§§ 3, 23, 38, 43, 48, 63). We find here the same doctrine of opposites which appears in the Phædo, and which has come up again and again in philosophy. We shall find something like it in the Sánkhya-karika of the Hindoos. The Duad, with the Monad brooding behind it, is the fundamental principle of the Avesta.