A veteran dyke-protection soldier heard this talk and also said with a sneer, “All stones fallen into the river must be looked for upstream. Because stone is solid and heavy while sand is loose and soft. Water cannot wash a stone away, but the force of its dashing against it can erode the sand and scoop a pit beneath it where it is exposed to the water, whose constant dashing and pounding keep it sinking deeper and deeper. When half of the stone is thus affected, it overturns into the sand pit. The water’s continuous scooping of the sand gives the stone one turn after another. Given the incessant overturning process, it is moved against the currents and travels up the river. To be sure, it is ludicrous to search for it downstream. But, is it not more so to look for it right on the river bed?” Acting upon his views, the stone animals were really found several li upstream. Similar cases in which one sees only one aspect and ignores other aspects of a phenomenon are too many to enumerate. Will it do to draw a conclusion from mere speculations? 作者简介：
纪昀，字晓岚。乾隆十九年(1754)进士。学问渊博，曾任翰林院编修、侍读学士。因获罪遣戍乌鲁木齐。释放回京后，任《四库全书》总纂官，编定《四库全书\总目提要》，在目录学上贡献很大。著有《阅微草堂笔记》等。
《阅微草堂笔记》是纪昀晚年所作的一部文言笔记小说，题材以妖怪鬼狐为主，但于人事异闻、名物典故等也有记述，内容相当广泛。
寻找石兽与流水侵蚀作用
清代学者纪昀在《阅微草堂笔记》中记载，某土地庙前石兽因河岸崩塌掉入河中。十多年后重修山门，寻找石兽，它却不在原落水处，也不在下游。一位老兵说，应该在上游寻找，依他的话，果然捞出了石兽。石兽为什么会向上游“跑”呢?原因在于，石兽落水后对水流形成阻力，使周围水速更快，冲刷能力更强，其下面迎水流一侧的泥沙逐渐被水冲走，成为空穴。久之，石兽因重力作用朝着迎水流的方向倾倒，如此再三，便向上游移动了一截。可见老兵的判断是正确的，流水的侵蚀和搬运作用，使石兽能“逆水而行”。