Eihei Dogen, also known as Dogen Zenji, was a Japanese Buddhist monk and the founder of the Soto Zen school in Japan. He is considered one of the most influential and revered figures in Japanese Buddhism, and his teachings have had a lasting impact on the practice of Zen.

Dogen's teachings revolve around the concept of zazen, or seated meditation, as the primary practice of Zen. He emphasized the importance of sitting in meditation as a means of directly experiencing the true nature of reality, rather than relying on intellectual understanding or theoretical knowledge.

One of Dogen's key teachings is the concept of "just sitting," which refers to the practice of sitting in meditation without any particular goal or purpose. This is in contrast to other forms of meditation that may have specific goals or techniques. Dogen believed that by simply sitting in meditation, one could awaken to their true nature and experience a state of inner peace and clarity.

Another important aspect of Dogen's teachings is the idea of non-duality, or the unity of all things. He taught that there is no separation between self and others, and that all beings are interconnected and part of the same universal reality. This concept is often expressed in his famous phrase, "to study the self is to forget the self, and to forget the self is to be enlightened by all things."

Dogen also emphasized the importance of mindfulness and being fully present in every moment. He believed that by being fully present and aware, one could experience the true essence of reality and find liberation from suffering. This is reflected in his teachings on the practice of everyday activities, such as eating and walking, as opportunities for mindfulness and awakening.

In addition to his teachings on meditation and mindfulness, Dogen also emphasized the importance of ethical conduct and compassion. He believed that the practice of Zen should not only benefit oneself, but also extend to others and the world around us.

Overall, Dogen's teachings revolve around the idea of awakening to one's true nature and living in harmony with the interconnectedness of all things. His teachings continue to be studied and practiced by Zen practitioners around the world, and his influence can be seen in the modern mindfulness movement.