A man from the state chu was crossing the river. in the boat, his sword fell
into the water by his carelessness. imediately he made a mark on the boat.“this
is where my sword fell off.”he said. when the boat stopped, he jumped into the
water to look for his sword at the place where he marked the boat. the boat had
moved but the sword had not. is this not a foolish way to look for a sword?

从前，一个楚国人在坐船过河时，不小心把他的剑掉入了水中。他马上在船上做了个记号。“这是我的剑掉下去的地方。”他说。船停下来后，他就根据船上的记号跳入水中寻找他的剑。船在移动但他的剑并没有。用这种方式来找剑难道不是非常愚蠢的吗?

刻舟求剑 【翻译】marking his mark.