Satori

[2][3] In the Zen Buddhist tradition, satori refers to a deep experience of kenshō,[4][5] "seeing into one's true nature".

[3] D. T. Suzuki, a Japanese author of books and essays on Buddhism, Zen and Shin that were influential in the West, described "... looking into one's nature or the opening of satori";[7] and said "This acquiring of a new point of view in our dealings with life and the world is popularly called by Japanese Zen students 'satori' (wu in Chinese).

In Japanese Buddhism, satori is a "first step" or embarkation toward Buddhahood: Ch'an expressions refer to enlightenment as "seeing your self-nature".

Koans are short anecdotes of verbal exchanges between teachers and students, typically of the Song dynasty, dealing with Buddhist teachings.

Wumen struggled for six years with koan "Zhaozhou's dog", assigned to him by Yuelin Shiguan (月林師觀; Japanese: Gatsurin Shikan) (1143–1217), before attaining kenshō.

After his understanding had been confirmed by Yuelin, Wumen wrote the following enlightenment poem:[13] A thunderclap under the clear blue sky All beings on earth open their eyes; Everything under heaven bows together; Mount Sumeru leaps up and dances.