Eihei Dogen, also known as Dogen Zenji, was a Japanese Buddhist monk who lived from 1200 to 1253. He is widely recognized as the founder of Soto Zen, one of the main schools of Zen Buddhism in Japan. Dogen's journey towards becoming the founder of Soto Zen was shaped by various experiences and teachings that he encountered throughout his life.

Dogen was born into a noble family in Kyoto, Japan. At a young age, he showed a deep interest in Buddhism and began studying under the guidance of the Tendai school of Buddhism. However, he soon became disillusioned with the teachings and practices of Tendai and began searching for a more authentic and direct experience of enlightenment.

In 1223, at the age of 23, Dogen traveled to China in search of a teacher who could guide him on his spiritual path. He studied under the guidance of the Chinese Zen master Rujing for two years and was deeply influenced by his teachings. Rujing's emphasis on the practice of zazen (sitting meditation) and the concept of shikantaza (just sitting) deeply resonated with Dogen and became the foundation of his own teachings.

After returning to Japan, Dogen faced resistance from the established Buddhist schools, who saw his teachings as a threat to their authority. However, with the support of his followers, Dogen established a small monastery in the mountains of Echizen, where he could freely teach and practice his own form of Zen.

In 1236, Dogen wrote his most famous work, the Shobogenzo (Treasury of the True Dharma Eye), which laid out the principles and practices of Soto Zen. This work, along with his teachings and the establishment of his own monastery, solidified Dogen's position as the founder of Soto Zen in Japan.

Dogen's teachings emphasized the importance of zazen as the primary practice for attaining enlightenment. He also stressed the idea of non-duality, the understanding that all things are interconnected and inseparable. This concept of non-duality is central to Soto Zen and is reflected in its emphasis on everyday mindfulness and the integration of Zen practice into daily life.

In conclusion, Eihei Dogen became the founder of Soto Zen through his own spiritual journey, which led him to study under a Chinese Zen master and eventually establish his own monastery and teachings in Japan. His emphasis on zazen, non-duality, and the integration of Zen into daily life continues to be a significant influence on Soto Zen practitioners today.