Who was the thinker of the Ming Dynasty who proposed the saying that "there is nothing outside the mind and there is no reason outside the mind"?

There is nothing outside the mind and no reason outside the mind. This is the basic view of Chinese philosophers in the Ming Dynasty.

Lu Jiuyuan proposed that "the heart is the principle" and "the universe is my heart, and my heart is the universe."

Wang Shouren developed these ideas of Lu Jiuyuan and proposed that "there is nothing outside the heart, nothing outside the heart, and no reason outside the heart." The "heart" mentioned by Wang Shouren refers to the highest ontology, such as "the heart is Tao, and Tao is heaven"; it also refers to personal moral consciousness, such as "the heart is just one, and it is called benevolence in terms of its overall compassion." In terms of its appropriateness, it is called meaning, and in terms of its order, it is called principle." This has a broader meaning than what Lu Jiuyuan said about personal intention.

Wang Shouren’s idea that there is nothing outside the mind means that the mind and things are of the same body. Things cannot exist without the heart, and the heart cannot exist without things. Without a clear mind, there will be no ghosts, gods, and all things in the world; without a clear mind, there will be no ghosts, gods, and all things in the world. On the one hand, the bright mind is the master of all things in the world; on the other hand, the heart has no body, and its body is the right and wrong that the world and all things sense. Objective things are in a state of emptiness if they are not perceived by the mind. Just like a flower in a deep mountain, if no one sees it, it will become silent with the heart; once someone sees it, the color of the flower will become clear for a moment.

Wang Shouren's "The Unreasonable Outside the Heart" means that the essence of the heart is the principle of heaven. Although things are different, the principle is in the heart, and the heart is the principle. There is no need to seek reason in things, seek reason outside the heart, that is, the heart and reason are two. The principle in the heart is the highest goodness, and the irrationality outside the heart means the lack of goodness in the heart.

Wang Shouren’s idea that there is nothing outside the mind and no reason outside the mind has developed the idealism of mind to the extreme, which laid the foundation of his cosmology for his theory of the unity of knowledge and action, and had a wide impact on later generations.