Tao Te Ching by Lao-Tzu. Introduction. "Sincere words are not fine; fine words are not sincere. Those who are skilled (in the Tao) do not dispute (about it); the disputatious are not skilled in it. Those who know (the Tao) are not extensively learned; the extensively learned do not know it."
Some ideas in this book might be very old, so old that they can only be said to have come from a very old man. These ideas were transmitted orally, in rhymed, easy to remember, aphorisms. They were transmitted through many mouths and minds; through those of simple peasants, shamans, hermits, and government officials. The sayings were thought over in many ways, interpreted in different manners, and applied in different situations. Some of the vocabulary underwent changes in its oral transmission, and some additions were made, whether consciously or by mistake. This adds to the elasticity of the original words. The book was finally written down in the third or second century B.C. The sayings in the present version of Lao Tzu may be approximately related to the several levels of human thought; Mystery, high philosophy, political theory, practical lessons for daily life, and health magics (physical and mental exercises). The mystery at the last level may lead back to the first level.
Text source: Introduction by Professor Chi-yun Chen, Professor Emeritus of Chinese History at the University of California, Santa Barbara.