Genjōkōan (現成公按[1]), translated by Tanahashi as Actualizing the Fundamental Point,[2][3] is an influential essay written by Dōgen, the founder of Zen Buddhism's Sōtō school in Japan.
According to Taigen Dan Leighton "The word genjo means to fully or completely manifest, or to express or share.
It's all mental and physical phenomena.... Kōan is derived from the word official document, and is meant to mean the unerring absolute authority of the Buddha-dharma.
[8] Thomas Cleary states that Genjōkōan begins with an outline of Zen using a presentation of the Five Ranks[4] claiming that Dogen used the device throughout his Shōbōgenzō.
[4] Shohaku Okumura says that in Genjōkōan "Dogen created a metaphor to express the reality of individuality and universality.