In the tenth month of 1082
苏轼 went back to the cliff with two friends. His wife brought out wine she had kept
以待子不时之需, 'for when you might suddenly need it', and they found the river had fallen:
山高月小,
水落石出, 'the hills high, the moon small, the water down and the rocks laid bare'. Both
不时之需 and
水落石出 became idioms.