1. The Changes is a book vast and great, in which everything is completely contained. The tao of heaven is in it, the tao of the earth is in it, and the tao of man is in it. It combines these three primal powers and doubles them; that is why there are six lines. The six lines are nothing other than the ways (tao) of the three primal powers.
2. The Way has changes and movements. Therefore the lines are called changing lines. The lines have gradations, therefore they represent things. Things are diverse; this gives rise to line characteristics. The line characteristics do not always correspond. From this arise good fortune and misfortune.
Here the places are divided according to the three primal powers. The first and the second line are the places of the earth, The third and the fourth those of man, the fifth and top line those of heaven; this division comes into consideration with the very first hexagram, THE CREATIVE. According to whether the lines of the different gradations are appropriate to the places, conclusions are drawn as to wethere they mean good fortune or misfortune. The chinese character for "line," hsiao, when written differently may also mean "to imitate." This is why the lines are here called "changing lines"--that is, lines oriented to the pattern of tao. The written character for hsiao consists of two sets of crossed lines, suggesting the crossing of yang and yin (爻).