The Book of Changes is a divination manual that became a philosophical classic, and the two functions have been carried together for two and a half thousand years.
Its units are the hexagram: six stacked lines, each broken for yin or unbroken for yang, giving sixty-four possible figures. Each hexagram is read as two trigrams, upper and lower, drawn from the eight three-line figures that stand for heaven, earth, thunder, water, mountain, wind, fire and lake. Each hexagram carries a judgment and an image, terse and often obscure, and each of its six lines carries its own line statement.
A consultation generates a hexagram by a randomising procedure. The older method sorts fifty yarrow stalks through a repeated division that takes some minutes per line; the common shortcut casts three coins six times. Both produce not only a line but its stability: a line may be young or old, and old lines are changing, converting to their opposite and so transforming the first hexagram into a second. The reader interprets the first figure as the present situation, the changing lines as where the pressure lies, and the second as the direction of movement. Consultation with no changing lines is read as a static situation.
The two methods do not produce identical probability distributions, a point noticed and argued about within the tradition and by modern commentators, since yarrow makes changing yang lines rarer than coins do.
What the text supplies is not an answer but an image to think against. Serious practice treats the terseness as the point: the figures are read against the question, and the work is done by the reader rather than by the book.