Kobutsushin

[1] It was presented to his students in the fourth month of 1243 at Rokuharamitsu-ji, a temple in a neighborhood of eastern Kyoto populated primarily by military officials of the new Kamakura shogunate.

Both were short works compared to others in the collection, and in both cases he was likely invited to present them at the behest of his main patron, Hatano Yoshishige, who lived nearby.

[2] He then supports this usage by citing examples from Zen records of the past teachers Tiantong Rujing, Yuanwu Keqin, Sushan Guangren, and Xuefeng Yicun.

[3] The second half of the text focuses on the full term used as the title of the book, Kobutushin (古佛心), literally "Old Buddha Mind".

He does so through the presentation of a famous saying from Nanyang Huizhong, the so-called "National Teacher", who said the old buddha mind is nothing other than "fences, walls, tiles, and pebbles", which is to say everyday reality and the phenomena that comprise it.