The master asked the monk to clean the garden.
The monk started with very big diligence, after a while he taught, the work was done, and asked the master if the garden is clean.
The master took some time to inspect and said it is not.
The monk starter all over, brushing, cleaning all the dust, until he thought everything was perfect. He asked the master again if he is done good job cleaning. But the master was negative again. The monk started again but was starting to get frustrated, after a good amount of time he asked the master if the garden is perfectly clean, and the master said that it is not.
Then the monk asked the master to tell him what is he do doing wrong.
The master went to the near tree, give it a good shake so some leaves fell down on the ground, and said to the monk, you should be able to accept the natural flow of things, they are already perfect.