Since there is only one heaven, the doubling of the trigram Ch'ien, of which heaven is the image, indicates the movement of heaven. One complete revolution of heaven makes a day, and the repetition of the trigram means that each day is followed by another. This creates the idea of time. Since it is the same heaven moving with untiring power, there is also created the idea of duration both in and beyond time, a movement that never stops nor slackens, just as one day follows another in an unending course. This duration in time is the image of the power inherent in the Creative.
With this image as a model, the sage learns how best to develop himself so that his influence may endure. He must make himself strong in every way, by consciously casting out all that is inferior and degrading. Thus he attains that tirelessness which depends upon consciously limiting the fields of his activity.