Turning Back at the Friend's Door
On a snowy night Wang Huizhi was seized by a wish to see his friend Dai Kui and travelled all night by boat, but turned home on reaching the door without going in. He explained that he set out on impulse and went back when the impulse was spent, so there was no need to actually see Dai. The anecdote treats the mood, not the stated goal, as the real purpose of an action, so an act can be complete once its feeling is used up.