XXXVIII. Attaining Principle Does Not Mean Everything Can Be Predicted

That the principle of all under Heaven is attained does not mean every detail of the future can be known in advance. The eight trigrams stir one another into motion, things influence one another, and human choice continually enters in as well, so that the concrete outcome is often unforeseeable. The Yi teaches a person to know the constant and comprehend change; it does not teach a person to boast of knowing everything. If "attaining principle" is understood as being able to control everything, one moves from revering Heaven to presuming upon Heaven.

Knowing principle lets a person know what must not be violated: the farming season must not be seized upon, the people's strength must not be exhausted, sincerity and trust cannot be deceived for long, what reaches its height must be guarded against, and what is faint at its beginning must be handled with caution. As for exactly when a rain will fall, how each step of a war will unfold, or when a particular person will have a change of heart, these still require observation as the matter unfolds. Principle provides direction and boundary; it does not eliminate the unknown.

The Sunzi holds that a victorious army first secures victory and only then seeks battle, stressing calculation in the temple and knowing both the enemy and oneself, and yet it also says that victory in war is never repeated in the same form, and that one must respond to the enemy's shape in boundless ways. The more thorough the preparation, the more one knows that, facing the actual enemy, one cannot simply copy old methods. One who truly knows principle is all the more cautious, because he sees how complex relations are; one who half-knows is instead prone to using a single piece of experience to judge the whole world.

Master Guiguzi's discernment of a person's speech and expression must also be repeatedly tested and confirmed; one cannot judge a person's whole life on the basis of a single probe. Human feeling has its constancy, and yet it can also be changed by interest, closeness or distance, fear, and shame. Knowing its constancy lets one prepare; seeing its change requires responding to it. Ease and simplicity give judgment its guiding thread; they do not give arbitrary conclusion an excuse.

Divination itself is likewise a seeking of clarity in the face of the unknown. If the future were entirely controllable, there would be no need for divination; if it were entirely without principle, divination would be of no use either. Precisely because change has its principle and yet remains concretely undetermined can a person, through the image of a hexagram, reflect on time and position and make a cautious choice. Drawing fortune in divination does not mean one may abandon effort; drawing misfortune does not proclaim inevitable defeat. Fortune and misfortune are born of gathering and dividing, advancing and withdrawing, and a person's own cultivation of virtue and correction of fault can still change the configuration that follows.

Reverent wariness before the unknown is part of ease and simplicity. True simplicity does not treat one's own model as though it were Heaven and Earth themselves; true ease does not exaggerate what is momentarily knowable into omniscience. Qian's knowing of the great beginning is grasping the fundamental point of departure; Kun's bringing things to completion demands entering the concrete process and accepting correction there. Only when knowing when to stop is matched with the ability to act does one truly attain principle.