Matsuo Basho is considered Japan’s finest composer of haiku. An awareness of the transience of life drove him to seek instruction in Zen from a master named Butcho. Basho briefly considered becoming a monk but in the end remained a layman. He did, however, commit himself seriously to the practice of zazen under Butcho’s direction.
Over and over Butcho would challenge Basho to express his understanding of Buddhism, and the student would reply by quoting sutras he had read while a student in Kyoto or by making reference to Chinese or Japanese Zen masters of the past.
“These are the words of others,” Butcho chided him. “Let me hear your words.”
Basho had no reply. Then one day, Butcho passed by the monastery pond where Basho was engaged in meditation. “How is your practice proceeding?” he inquired.
Basho automatically answered poetically. “After the rains, the grass is greener than ever.”
“So,” Butcho shot back, “tell me of the nature of Buddhism before the greenness of the grass.”
Basho was stymied for a moment. Then the event took place which brought him to awakening. There was a splash in the pond. “A frog jumps into the water,” Basho said. “Hear the sound!”
Later he re-worked this into his best known koan—which is even briefer in its English rendition than it is in Japanese.
An old pond
A frog jumps in
[Matsuo Basho – Zen Masters of Japan: 212-21]