This text investigates the fundamental nature of reality and the practice of zazen as articulated by the 13th-century Japanese Zen master Dogen. The author, a seminal figure in the Soto school of Zen Buddhism, utilizes a rigorous philosophical framework to dismantle the distinction between practice and enlightenment. By examining the ontological status of the self and the environment, Dogen argues that the act of sitting meditation is not a means to an end, but the manifestation of the Buddha-nature itself.

Scholars and practitioners consider this work a foundational text for understanding the intellectual depth of Soto Zen. Readers frequently note the density of the prose, which requires careful study to grasp the nuances of Dogen's unique linguistic style.