Eihei Dogen was a 13th century Buddhist monk and the founder of Soto Zen in Japan. His philosophy was centered around the idea of "zazen" or seated meditation as the ultimate path to enlightenment.

Dogen believed that the true nature of reality could only be realized through direct experience, rather than through intellectual understanding or studying scriptures. He saw zazen as a way to directly experience the present moment and to let go of the distractions and attachments of the mind.

In his teachings, Dogen emphasized the importance of "shikantaza" or "just sitting" in zazen, without any goal or expectation. He believed that by fully immersing oneself in the present moment, one could achieve a state of "samadhi" or complete absorption, leading to a deeper understanding of the true nature of reality.

Dogen also emphasized the concept of "non-duality" in his philosophy, which means that there is no separation between the self and the world. He believed that by letting go of the ego and the idea of a separate self, one could experience the interconnectedness and interdependence of all things.

Another key aspect of Dogen's philosophy was the importance of ethical conduct. He believed that true enlightenment could only be achieved through living a moral and compassionate life, treating all beings with kindness and respect.

Dogen's teachings also emphasized the impermanence and constant change of all things. He saw this as a reminder to fully embrace and appreciate the present moment, as it is constantly passing and cannot be grasped or held onto.

Overall, Dogen's philosophy revolved around the idea of experiencing the present moment fully and letting go of attachments and distractions of the mind. Through zazen and ethical conduct, one could achieve a deeper understanding of the true nature of reality and ultimately, enlightenment. His teachings continue to be a fundamental aspect of Soto Zen practice in Japan and around the world.