Eihei Dōgen’s teaching turns again and again to zazen, especially the practice known as shikantaza, or “just sitting.” Seated meditation is not presented as a technique to acquire some later result, but as the very manifestation of enlightenment itself. In this sitting, one does not strive, manipulate thoughts, or chase special experiences; one simply maintains upright posture and clear awareness, allowing body and mind to settle. This is why Dōgen can speak of “dropping off body and mind” (shinjin datsuraku): when grasping and self-centered intention relax, the habitual sense of a fixed “me” falls away of its own accord. Zazen, in this light, is not a preparation for awakening but the activity of Buddha already at work.

From this flows Dōgen’s insistence on the unity of practice and enlightenment, sometimes expressed as shushō-ittō. Practice does not stand on one side and enlightenment on the other; each moment of wholehearted practice is complete realization. This view is grounded in his teaching on Buddha-nature, the claim that all beings already possess inherent awakening. Practice does not manufacture Buddha-nature but reveals and actualizes what is already present. Because of this, he criticizes a “gaining mind” that seeks spiritual achievements as if they were possessions, and he warns against relying on mere intellectual understanding without embodiment in lived practice.

Dōgen’s reflections on “being-time” (uji) deepen this vision. Being and time are not two separate dimensions but a single dynamic reality in which each moment is a complete expression of all existence. Past, present, and future are not fixed, independent blocks; each “now” is all-inclusive and alive. In this sense, to live fully in the present is not a narrow focus on a fleeting instant, but an intimate participation in the whole fabric of reality. Every phenomenon, from a flower blooming to a stone resting, can be understood as the total exertion of Buddha-nature in that moment.

Because enlightenment is not elsewhere, Dōgen gives great weight to everyday conduct and communal life. Monastic discipline, work, eating, hygiene, and all ordinary activities become fields of practice when carried out with precise attention and proper mind. Texts attributed to him describe detailed regulations for such activities, not as mere rules, but as concrete forms through which the Dharma is embodied. Study of teachings and scriptures is valued, yet always subordinate to direct realization through practice and the living transmission that occurs beyond words. In this way, the “koan” is not confined to formal riddles, but is found in the very circumstances of daily life, where the self is studied, forgotten, and realized through the myriad things.