The moral of carving a boat for a sword:
It is common sense that a sword will sink only when it falls into the water. It's ridiculous to look under the bottom of the boat for a sword that has long fallen into the water when it's far away. If the ship is stationary and the sword sinks to the bottom of the water, mark the place where the ship fell, and you can naturally find the sword. But the sword sank to the bottom of the water and stopped, but the ship moved on. This objective fact is not reflected in the mind of the sword seeker. He is bent on finding the sword where it fell, and he will find it. His understanding is inconsistent with the objective facts, and the result is naturally failure. It is very powerful to use such a metaphor to satirize people who cling to dogma.
This idiom has two meanings. One is that if people's ideological understanding does not conform to the objective reality, they will not succeed in doing things. On the other hand, objective reality is constantly developing and changing. If we regard the old rules and regulations as a magic weapon to solve new problems, we should also make jokes. The author's thoughts are simple materialism and dialectics.