"Treasury of the True Dharma Eye"), the collection of works written in Japan by the 13th century Buddhist monk and founder of the Sōtō Zen school, Eihei Dōgen.
It was written on the 19th of April, 1242 at Dōgen's monastery Kōshōhōrin-ji in Kyoto.
[1] The book appears as the 12th book in the 75 fascicle version of the Shōbōgenzō, and it is ordered 27th in the later chronological 95 fascicle Honzan editions.
Hongzhi's poem is quoted verbatim in Dōgen's Zazen shin and also presented again in modified form later in the text.
Later in the text Dōgen comments on the story of Chan master Mazu Daoyi who likened trying to become a Buddha through meditation with polishing clay tile to make a mirror, something which is impossible and does not make sense.