three days before and after a change

“Three days before and after a change” is a rule for approaching a consequential turning point: investigate the conditions that brought it about, announce or weigh the proposed change in advance, and review what follows. In the commentary on Kû, the rule turns a prediction of progress into a disciplined process of diagnosis and correction; in the Great Treatise, it appears as guidance attached to firm and correct action.

Meaning and Use

The phrase does not prescribe a change in isolation. Its before-and-after structure makes deliberation part of the action itself: prior attention is directed toward the circumstances producing the turn, while subsequent attention tests the measures taken. In the account of Kû, this is especially important because the condition represented is one of decay that must be arrested and restored to soundness. The change is therefore not simply an opportunity for forward movement; it calls for understanding how disorder arose and for judging whether the remedy works.

The rule also distinguishes purposeful action from a reliance on divination as a means of learning the future absolutely. The book’s account of divination describes consultation as testing whether contemplated plans and conditions are likely to turn out favorably or unfavorably, not as discovering future events with certainty. Read in that context, the three-day instruction directs attention back to the consulter’s proposed course: preparation and review accompany judgment about whether to proceed.

The Instruction in Kû

Kû promises great progress and success to one who deals properly with the represented condition, and says there will be advantage in an effort like crossing a great stream. The warning about the days before and after the turning point qualifies that auspicious prospect. Crossing the stream signifies the scale of effort required; the temporal instruction adds that success depends on considering both the causes of the trouble and the actions chosen to remedy it.

The commentary explains the hexagram as a state in which things are going to ruin, as if through poison or venomous worms, and interprets its favorable outcome as the arrest of decay and restoration to health and vigor. Such recovery requires great efforts, but effort alone is not enough: one must carefully consider what brought on the decay and what measures should address it. The three-day rule thus links diagnosis to intervention, rather than treating the auspice of progress as an unconditional guarantee.

A Recurring Rule of Change

The same temporal formula appears in the fifth line of the Gentle and Penetrating. There, firm correctness brings good fortune, repentance disappears, and movements become advantageous; even when the beginning has not been good, a good ending remains possible. The line instructs its subject to give notice of changes three days before making them and to reconsider them three days afterward. Here the rule is made explicitly procedural: communicate beforehand, then review afterward.

The two contexts give the instruction complementary force. Kû emphasizes tracing the origins of a damaged condition and weighing the remedy; the fifth line of the Gentle and Penetrating emphasizes notice and reconsideration. Together they frame change not as a single decisive moment but as a sequence of preparation, action, and renewed judgment. The favorable ending depends on sustained responsibility across that sequence.