There was once a great master of kenjutsu (sword) renowned throughout Japan who, when visited by another great master, wished to demonstrate the teaching he had given his three sons.
The master winked at his guest and placed a heavy metal vase on the corner of the sliding doors, wedged it with a piece of bamboo and a small nail in such a way that the vase would fall on the head of the first one who came into the room when the door was opened.
While chatting and drinking tea, the master called his oldest son who came immediately. Before opening the door, he felt the presence of the vase and its position. He slid back the door, put his left hand through the gap to catch the vase and continued opening the door with his right hand. Then, clutching the vase to his chest, he entered the room, shutting the door behind him and replacing the vase; he came forward and greeted the two masters. ‘This is my oldest son’, said the host smiling, ‘he has learnt my teaching well and one day he will undoubtedly be a master of kenjutsu.’
The second son was called and he entered without hesitating and only caught the vase at the last moment: it almost landed on his head. ‘This is my second son’, said the master, ‘he still has a lot to learn but he is improving every day.’
Then the third son was called. Entering the room hurriedly, he was struck on the head by the vase. The blow was a heavy one but before the vase hit the tatami, he drew his sword and, in one quick action, cut the piece of metal in two. ‘This is my youngest son, Jiro’, said the old man, ‘he is the baby of the family and he still has a long way to go.’