In ancient times, a man from the State of Chu crossed the river by boat and accidentally dropped his sword into the river. The people on the ship were very surprised, but this person remained calm and collected. He found a small knife from his body and crouched on the side of the ship where his sword had fallen into the water. He carved a mark on the outside of the ship, saying, “My sword fell from here. When the ship reaches the shore, I will go down here to look for it and I will definitely find it.”
The people on the ship were very puzzled. They wanted to comfort him, but to their surprise, the man was so calm and unique in his actions.
When the ship arrived at the shore, the man hurriedly took off his clothes and plunged into the water from the marked spot on the ship to search for his sword. Repeating several times, the man gained nothing. Everyone laughed and said, “Your sword fell into the water, and if you jumped down at that time, you might still be able to find it. But then, as the ship sailed, your sword sank to the bottom of the water and wouldn't follow. How could you find it.”
This idiom contains two layers of truth. On the one hand, if a person's thinking and understanding do not conform to objective reality, they will not succeed in doing things. On the other hand, objective reality is constantly evolving and changing. If we use old rules and regulations as a magic weapon to solve new problems, it would also result in failure.
This idiom tells us to approach problems dialectically, not only focusing on subjective efforts, but also valuing changes in objective facts.
古时，有个楚国人乘船渡江，一不小心把身上的佩剑掉进了江水中。船上的人很是惊讶，可这个人不慌不忙，从身上翻找出一把小刀子，蹲在佩剑掉落水中的船舷边，在船舷的外面刻了一个记号，说：“我的剑是从这里掉下去的，船到岸后，我就从这里下去找，一定会找到的。”
船上的人很是不解，本来想安慰其一番，却不想此人如此的从容，做事如此地别具一格。
待船到了岸，此人急急忙忙脱掉衣服，从船上刻有记号的那个地方，一个猛子扎到水中去找寻他的佩剑。反复几次，都毫无所获。众人都嘲笑起来：“你的剑掉入水中，那时你若跳下去还可能找得到。可那以后，船在行驶，你的佩剑沉在水底，不会跟着走。你又如何找得到？”
这则成语包含着两层道理。一层是，人的思想认识如果不符合客观实际，就不会把事情做成功。另一层是，客观实际是不断发展变化的，如果把陈规旧章当成解决新问题的法宝，也是要闹笑话的。
这个成语告诉我们，要辩证地看问题，不能只注重主观上的努力，更要重视客观事实的变化。
