In the beginning of Dogen’s Bussho fascicle of the Shobogenzo, he quotes a famous passage from the Nirvana Sutra (ch. 27). All sentient beings without exception have the Buddha-nature. In Dogen’s way, Dogen reinterprets this sentence so that it more explicitedly reads in a non-dualistic style. In the previous sentence, it’s possible to read it dualistically as:
A subject, “sentient beings” “has” an object, “Buddha-nature”
Dogen reinterprets the sentence as: Entire being is the Buddha-nature. He tries to alleviate the duality inherent in the sentence structure. Entire being becomes the complete network of interdependent co-origination, which has no inside and no outside, no I and no you. Our being or a sentient being is actually the same as the total dynamic working of the entire network of beings. We cannot pull out a separated “being”. Dogen deconstructs the space or place of a “being” as a separate, independent unit. The entire network of beings, functioning together, is the Buddha-nature.
The Buddha-nature is not seen as a “thing” or an “object” but rather the process of life life-ing itself. It is the total dynamic working of the machine of life. Katagiri Roshi deconstructs the “time” of Buddha-nature. He says :
“Buddha-nature is impermanence itself. This real moment is constantly: working, arising, disappearing, and appearing. To say what the present moment is, right here, right now, is to say that this moment has already disappeared. This is called emptiness. Both cause and effect are exactly impermanence in themselves. It means just appearing, that’s all. This is the basic nature of existence. That’s why impermanence is Buddha-nature. Buddha-nature is being preached constantly. When you manifest yourself right now, right here, becoming one with zazen or with your activity, this is Buddha-nature manifested in the realm of emptiness or impermanence.”
— From Returning to Silence, page 9.