Dogen, the founder of Soto Zen Buddhism in Japan, is known for his teachings on the concept of "non-duality." This concept is central to his philosophy and has great significance in understanding his teachings and approach to Zen practice.

At its core, non-duality refers to the idea that there is no separation or distinction between the self and the external world. It is the understanding that all things are interconnected and interdependent, and that the boundaries we perceive between ourselves and others are ultimately illusory.

For Dogen, this concept is closely tied to the Buddhist principle of emptiness, which states that all phenomena are devoid of inherent existence. In other words, everything is constantly changing and interconnected, and there is no fixed or permanent self or reality.

One of the key ways in which Dogen expressed the concept of non-duality is through his teachings on "practice-enlightenment." He believed that the practice of meditation and the attainment of enlightenment were not two separate things, but rather one and the same. In other words, the ultimate goal of meditation is not to achieve some higher state of consciousness, but to fully immerse oneself in the present moment and realize the non-dual nature of reality.

Another important aspect of Dogen's concept of non-duality is his emphasis on the unity of body and mind. In many spiritual traditions, the body and mind are seen as separate entities, with the mind being seen as more important or valuable. However, Dogen taught that the body and mind are inseparable and that both are essential in the practice of Zen. This understanding helps to break down the dualistic thinking that often separates the physical and spiritual aspects of our lives.

The concept of non-duality also has practical implications for how we live our lives. Dogen believed that by recognizing the non-dual nature of reality, we can let go of our attachments and desires, and find true peace and contentment. This is because when we see ourselves as separate from others and the world around us, we are constantly striving and grasping for things that we believe will make us happy. But when we see through this illusion of separation, we can find contentment in simply being present and accepting things as they are.

In conclusion, Dogen's concept of non-duality is a fundamental aspect of his teachings and has great significance in understanding his approach to Zen practice. It challenges us to see beyond the illusion of separation and to embrace the interconnectedness of all things. By doing so, we can find true peace and contentment in the present moment.