Eihei Dogen (1200-1253) brought what is now called the Soto school of Zen Buddhism to Japan from China. He wrote the first important Buddhist works in Japanese (rather than Chinese), and his masterwork, the Shobogenzo, is considered to be both a literary and religious classic. He founded the temple of Eiheiji.
The first fascicle ('chapter') in the Shobogenzo is Genjokoan. Many scholars believe that it contains the essence of the rest, and that is my own take on it. When I first encountered it in the Nishiyama and John Stevens translation, I was immediately struck by it. For a long time, I could not get beyond the first paragraph. I knew that I had encountered something particularly important for my spiritual development.
One evening, I started to type the first paragraph in order to either send it to someone, or put it on my web pages, I can no longer remember exactly. In any case, I found that I couldn't stop, and for the first time read it through to completion as I typed it. As I did so, I had the distinct feeling that Dogen himself was speaking directly to me, not just to the lay person for whom it was presumably written. While this was going on, I also had the experience of directly understanding (or at least feeling as if I did) some of what was 'underneath' the words.
Here is a translation by Nishiyama and John Stevens which is 'descended' from the file I typed that night.