from The Treasury of the True Dharma Eye: Zen Master Dogen's Shobo Genzo, by Dogen Zenji, edited by Kazuaki Tanahashi.
Arousing the aspiration for enlightenment is making a vow to bring all sentient beings [to the shore of enlightenment] before you bring yourself, and actualizing the vow. Even a humble person who arouses this aspiration is already a guiding teacher of all sentient beings.
This aspiration is neither originally existent nor does it emerge all of a sudden. It is neither one nor many. It is neither spontaneous nor formed gradually. This aspiration is not in yourself, nor are you in it.
This aspiration is not pervasive in this world of phenomena. It is neither before nor after. It is neither existent nor nonexistent. It is neither self nature nor other nature. It is neither common nature nor causeless nature.
Yet, in response to affinity [between the teacher and the student], the aspiration for enlightenment arises. It is not given by buddhas or bodhisattvas, and it is not created by yourself. The aspiration arises in response to affinity, thus it is spontaneous.
This aspiration for enlightenment has been aroused mostly by humans who live in the Southern Continent, Jambudvipa. It has also been aroused by those who abide in the eight difficult situations [to attain enlightenment], but not by most of them.
After arousing the aspiration for enlightenment, bodhisattvas practice for many eons, for one hundred great eons. They practice for countless eons, become buddhas, awaken, and benefit sentient beings through this bodhisattva determination.