The book attributed to Laozi, the Daodejing, Classic of the Way and Its Power, also romanised Tao Te Ching, is short, around five thousand characters in eighty-one brief chapters, and its influence is out of all proportion to its length.
Its themes extend well beyond the two famous terms. It prizes the soft over the hard and the yielding over the rigid, taking water as its model, weakest of things, yet wearing away stone. It praises the uncarved block and the uncarved life, the usefulness of emptiness (the use of a vessel is the space inside it), and a receptive, "feminine" principle it sets above force. Much of it is addressed to rulers, counselling a government so light that the people barely know it is there. Alongside the roughly contemporary Zhuangzi, whose wit and parable complement the Daodejing's aphorism, it forms the core of what later scholars grouped as the daojia, the philosophical current of Daoism.
Its reach outside China is remarkable. By one common count the Daodejing is among the most translated books in the world, with well over a hundred English versions alone, and it has been read by figures as far apart as Heidegger, who worked on a translation, and the Western counterculture, which took it up in the twentieth century. Some of that reception rests on paraphrase and projection, but the appetite is real: a text that opens by warning that the Way which can be spoken is not the constant Way has been spoken about more than almost any other.