The I Ching, or Book of Changes, is one of the oldest Chinese classics: at its core a Western Zhou divination manual of sixty-four hexagrams, each a figure of six broken or unbroken lines. Only centuries later did a set of commentaries, the Ten Wings, read those omens as a cosmology of yin, yang, and ceaseless change, turning the oracle into a treatise on change itself. Enrolled among the Five Classics under the Han, it has been consulted, in evolving forms, for roughly three millennia, at once a working oracle and a book of wisdom.
Most books are meant to be read from the first page to the last. The Book of Changes is meant to be met by chance. You hold a question in mind, sort a bundle of dried yarrow stalks or toss three coins six times, and the fall of the lines sends you to one of sixty-four short, riddling passages. For close to three thousand years, through one evolving version of the text after another, a farmer seeking a marriage date and an emperor weighing a war have come to the book the same way, trusting that the pattern the stalks happened to make was not an accident at all, but the true shape of the moment they were living through.