Eihei Dogen (1200-1253) was the founder of the Soto Shu, a Japanese school of Zen based on a Chinese tradition. He was an important philosopher and his major work was called the Shobogenzo.
Dogen was an illegitimate son of a high official, Minamoto Michitomo. His mother died when he was seven years old.
He ordained as a Tendai monk. The Tendai Shu taught that all beings are intrinsically endowed with Dharma Nature. Dogen became preoccupied with the question, if this is so, why do Buddhas need to teach?
Not finding an answer, he went to study Rinzai Zen under the master Myozen who was the successor of Eisai, the founder of Rinzai Shu in Japan.
In 1223, Myozen and Dogen travelled together to China seeking further teachings. In those days this was a hazardous journey.