The mind is principle. How can there be affairs or principles outside the mind?
"The mind is principle. How can there be affairs or principles outside the mind?"
爱问：「『知止而后有定』，朱子以为『事事物物皆有定理』，似与先生之说相戾。」
先生曰：「于事事物物上求至善，却是义外也。至善是心之本体，只是明明德到至精至一处便是，然亦未尝离却事物。《大学》所谓『格物致知』者，致吾心之良知于事事物物也。吾心之良知，即所谓天理也。致吾心良知之天理于事事物物，则事事物物皆得其理矣。致吾心之良知者，致知也。事事物物皆得其理者，格物也。是合心与理而为一者也。」
「若鄙人所谓致知格物者，致吾心之良知于事事物物也。致吾心良知之天理于事事物物，则事事物物皆得其理矣。致吾心之良知者，致知也。事事物物皆得其理者，格物也。是合心与理而为一者也。合心与理而为一，则凡区区前之所云，与朱子之云者，皆可不言而喻矣。」
Xu Ai asked: "The Great Learning says 'When you know where to rest, you become settled.' Zhu Xi interprets this as 'all things have their fixed principles,' which seems to contradict your teaching."
The Master said: "To seek the supreme good in things is to hold that righteousness is external. The supreme good is the original substance of the mind — it is simply the bright virtue refined to its utmost purity and unity, yet it never departs from things. What the Great Learning calls 'investigating things and extending knowledge' means extending the innate knowledge of my mind to all things. The innate knowledge of my mind is what is called heavenly principle. When I extend the heavenly principle of my innate knowledge to all things, then all things attain their principle. Extending the innate knowledge of my mind is extending knowledge. All things attaining their principle is investigating things. This is uniting mind and principle as one."
When facing moral dilemmas, you don't need to consult every ethical treatise. Quiet your mind and ask your innate knowledge — you already know deep down what is right. Yangming's "mind is principle" is about trusting your inner moral compass.
Great leaders don't pile up rules and processes (seeking principle in things). Instead, they cultivate their own judgment and insight (extending innate knowledge). Systems are tools; the leader's innate knowledge is the foundation.
"The mind is principle. How can there be affairs or principles outside the mind?"
This is the first proposition of Yangming's School of Mind. Zhu Xi's school held that "nature is principle" — principle exists in the things of the world, and the mind recognizes it through investigation. Yangming reverses this direction: principle is not outside the mind; the mind itself is the source of principle.
"To seek the supreme good in things is to hold that righteousness is external."
Yangming directly identifies the difficulty in Zhu Xi's approach: if the supreme good must be sought in each thing, then moral principles are external — precisely the position of Gaozi that Mencius refuted. Yangming uses Mencius against Zhu Xi, a strategically brilliant argument.
"Extending the innate knowledge of my mind to all things."
This is Yangming's completely new interpretation of "investigating things and extending knowledge." Investigation is not about exhaustively studying external principles, but about extending the innate knowledge of the mind to each thing. Facing your father, innate knowledge naturally manifests as filial piety. It is not that you first learn "the principle of filial piety" and then practice it.