Dōgen’s teaching on non-duality is not presented as an abstract doctrine but as the very texture of awakened life as it unfolds in practice. At its heart stands the unity of practice and enlightenment: genuine zazen is not a step toward some later awakening, but the present manifestation of Buddha-nature itself. This overturns the imagined gap between an “ordinary practitioner” and a “future enlightened one,” revealing that the act of wholehearted sitting already enacts realization. In this sense, the separation between seeker and sought falls away, and practice is understood as practice-realization, a single, indivisible event.

From this perspective, the usual boundaries that define experience begin to soften. Dōgen emphasizes that to study the self is to forget the self, and in that forgetting, self and all things are actualized together. The apparent division between “subject in here” and “object out there” is exposed as a conceptual construction, and the lived field of experience appears as a dynamic, interdependent whole. This “dropping off body and mind” is not an escape from the world but a way of meeting it without the filter of dualistic judgment.

Dōgen’s reflections on being-time (uji) further deepen this non-dual vision. Time is not a neutral container in which beings reside; rather, each being is its time, and each moment is complete being-time. Past, present, and future are not separate compartments but interpenetrating expressions of Buddha-nature in the immediacy of this moment. In such a view, there is no need to search for a reality behind appearances, because reality as it appears right now is already the full manifestation of truth.

Within this framework, the distinction between samsara and nirvana, or between ordinary phenomena and ultimate reality, loses its hard edge. Delusion and enlightenment are not two separate realms but different ways of experiencing and enacting the one reality that is always present. Emptiness is not a hidden realm behind forms; it is precisely these forms themselves when seen without clinging. Thus, non-duality in Dōgen’s thought undergirds the Soto Zen emphasis on “just sitting” (shikantaza): a goalless, wholehearted engagement in which every moment of ordinary life is allowed to stand as the unobstructed functioning of Buddha-nature.