A man, who came from the State of Chu, was sitting in a boat preparing to cross a river when he accidentally dropped his sword into the water. He immediately made a mark on the side of the boat at the place where his dear sword fell. When he returned close to shore, he entered the water just beneath the mark which he made. Naturally the sword, which he dropped in the river, has gone far away because the boat and the river are in motion. The man made the mark on the moving boat to look for his sword, which sounds so ridiculous.