大般涅槃経
Dōgen begins his work by quoting the putative words of Shakyamuni Buddha as recorded in the Mahāyāna Mahāparinirvāṇa Sūtra stating that all living beings have buddha nature. He then equates this statement to a dialogue Dōgen often cites between Nanyue Huairang and his teacher Dajian Huineng in which they discuss the undefiled nature of "practice and verification" (), setting up his argument that buddha nature is just reality itself.