One day, a man came to a door. He opened the door. And behind the door he found: a room. Yes. A perfectly silent room. This story continues... in hell.
The koan: "Accurate Proportion"
Sen no Rikyu, a tea-master, wished to hang a flower basket on a column. he asked a carpenter to help him, directing the man to place it a little higher or lower, to the right or left, until he had found exactly the right spot. "That's the place," said Sen no Rikyu finally.
The carpenter, to test the master, marked the spot and then pretended he had forgotten. Was this the place? "Was this the place, perhaps?" the carpenter kept asking, pointing to various places on the column.
But so accurate was the tea-master's sense of proportion that it was not until the carpenter reached the identical spot again that its location was approved.
The enlightenment: So this guy was good at making tea and he had adequate spatial memory. Okay then.
I guess if you wanna learn about zen there are books and whatnot.
This has been "Zen Koans Explained." The bump, or the log?