A teacher said, “It’s like filling a sieve with water.”
The student thought about this for some time, but didn’t understand. The teacher took a sieve and they went to the sea.
The student poured water into the sieve and it poured out again.
“How do you do it?” she asked.
The teacher threw the sieve out into the ocean, where it floated for a moment and then sank.
– PZI Miscellaneous Koans, Case 58