Answer: From olden times down to the present day, all who were ever enlightened, either by colors or sounds, practised Zazen without Zazen and became instantaneously enlightened.12
What exactly is he saying here? It would seem that he is convoluting the early teaching of the Southern sect, which proposed that "meditation" is a mind process that might also be duplicated by other means. Dogen seems to be arguing that zazen is efficacious since all who became enlightened were really "meditating" in daily life, whether they realized it or not. The Southern school claimed that dhyana could be anything and therefore it seemed ancillary; Dogen claims it could be anything and therefore it is essential.
Dogen also came back to his original doctrinal dilemma, the question that had sent him wandering from teacher to teacher in Japan while still a youth: Why strive for enlightenment if all creatures are Buddhas to begin with? He finally felt qualified to address his own quandary.
Question: There are those who say that one has only to understand that this mind itself is the Buddha in order to understand Buddhism, and that there is no need to recite the scriptures or undergo bodily training. If you understand that Buddhism is inherent in yourself, you are already fully enlightened and there is no need to seek for anything further from anywhere. If this is so, is there any sense in taking the trouble to practice Zazen?
Answer: This is a very grievous mistake, and even if it should be true and the sages should teach it, it is impossible for you to understand it. If you would truly study Buddhism, you must transcend all opinions of subject and object. If it is possible to be enlightened simply by knowing that the self is, in its self-nature, the Buddha, then there was no need for Shakyamuni to try so diligently to teach the Way.1
Whether this answer resolves the paradox will be left to the judgment of others. But for all his intensities and eccentricities, Dogen was certainly a powerful new thinker, clearly the strongest dialectician in the history of Japanese Zen. He was also a magnetic personality who attracted many followers, and by 1233 he had so outgrown the space at An'yoin that a larger temple was imperative (which became available thanks to his aristocratic connections). His next move was to Kosho-ji, a temple near Kyoto, where he spent the succeeding ten years in intense literary creativity, where he constructed the first truly independent Zen monastery in Japan, and where he found a worthy disciple, Koun Ejo (1198-1280), who served as head monk and ultimately as his successor. It was here, beginning in 1233, that Dogen finally recreated Chinese Ch'an totally in Japan, right down to an architectural replica of a Sung-style monastery and an uncompromising discipline reminiscent of his old Chinese master Ju-ching.
After settling in at Kosho-ji he began, in late 1235, a fundraising drive for the purpose of building the first Zen-style monks' hall (sodo) in Japan. He believed that this building, viewed by the lawgiver Po-chang Huai-hai as the heart of a Ch'an monstery, was essential if he were to effectively teach meditation. The doors would be open to all, since the onetime aristocrat Dogen was now very much a man of the people, welcoming rich and poor, monks and laymen, men and women.14
When the meditation hall opened in 1236, Dogen signaled the occasion by posting a set of rules for behavior reminiscent of Huai-hai's laws set down in eighth-century China. A quick skim of these rules tells much about the character of the master Dogen.