‘Just sit as if you were the boundless empty sky or a ball of fire. Trust everything to the inhalation and exhalation. Even if eighty-four thousand idle thoughts arise, each and every one may become the Light of prajna (undiscriminating wisdom) if you do not pay them any attention and simply let them go.
Not only in sitting, but every step you take is the movement of the Light. Step after step, no discrimination… To inhale or to exhale, to listen or to touch, being without thoughts and discrimination is nothing other than the tranquil illumination of the Light in which body and mind are one. Therefore, when someone calls, you answer. This is the Light in which ordinary people and sages, the deluded and the enlightened, are one.
Even in the midst of change, the Light is not hindered by it. Forests, flowers, grass, and leaves; human beings or animals, big or small, long or short, square or round: all manifest themselves simultaneously, independent of discriminating thoughts or will.’ (Komyozo-Zanmai -Samadhi of the Treasury of the Radiant Light)
Koun Ejo was Dogen’s successor (if you want much more detail, Wikipedia as usual has it – generally speaking it is really helpful for reading up on some Buddhist facts), and we should be grateful to him for recording Dogen’s spoken words in Shobogenzo Zuimonki, Eihei Koroku, and Eihei Shingi (Dogen wrote down the fascicles of the Shobogenzo himself, which is what makes them that much harder to grapple with). I was particularly drawn to the last line, harking back a few more generations to Dongshan (Tozan in Japanese).