Exhausting the mind comes from knowing nature; extending knowledge lies in investigation.
"Exhausting the mind comes from knowing nature; extending knowledge lies in investigation of things."
爱问：「『尽心由于知性，致知在于格物』，何也？」
先生曰：「此须认得心体明白。心之本体即是性，性即是理。穷仁之理，真要仁极仁；穷义之理，真要义极义。仁义只是吾性，故穷理即是尽性。尽心由于知性者，以其理之凝聚而言则谓之性，以其凝聚之主宰而言则谓之心，以其主宰之发动而言则谓之意，以其发动之明觉而言则谓之知，以其明觉之感应而言则谓之物。故就物而言谓之格，就知而言谓之致，就意而言谓之诚，就心而言谓之正。正心者，正其心之不正以归于正也。诚意者，实其心之所发而毋自欺也。致知者，致其心之良知也。格物者，格其心之不正以归于正也。」
Xu Ai asked: "Regarding 'exhausting the mind comes from knowing nature, and extending knowledge lies in investigation,' what does this mean?"
The Master said: "One must clearly understand the original substance of the mind. The original substance of the mind is nature, and nature is principle. To exhaust the principle of benevolence, one must truly reach the utmost benevolence; to exhaust the principle of righteousness, one must truly reach the utmost righteousness. Benevolence and righteousness are simply our nature, so exhausting principle is exhausting nature. The reason exhausting the mind comes from knowing nature is: from the perspective of principle's凝聚 it is called nature; from the perspective of the master of that凝聚 it is called mind; from the perspective of that master's activation it is called intention; from the perspective of that activation's clear awareness it is called knowledge; from the perspective of that clear awareness's response it is called thing. So from the perspective of things it is called investigation; from the perspective of knowledge it is called extending; from the perspective of intention it is called sincerity; from the perspective of mind it is called rectification. Rectifying the mind means rectifying what is incorrect in the mind to return to correctness. Sincerity of intention means making the mind's emanation real without self-deception. Extending knowledge means extending the mind's innate knowledge. Investigation of things means rectifying what is incorrect in the mind to return to correctness."
Yangming's conceptual system tells you: your mind, nature, principle, knowledge, intention, and things are unified. You don't need to seek answers outside — all answers are in your heart. When facing complex problems, return to the inner mind and let innate knowledge guide you.
"Exhausting the mind comes from knowing nature."
Yangming unites the concepts of mind, nature, and principle: the mind's original substance is nature, and nature is principle. These three are different aspects of the same reality — like water, ice, and steam are different forms of the same substance.
"From the perspective of principle's condensation it is called nature."
This passage establishes a complete conceptual system: principle → nature → mind → intention → knowledge → thing. These are not different things, but different names for the same reality from different angles. Understanding this helps understand why "rectifying the mind, making intention sincere, extending knowledge, investigating things" are actually the same thing from different perspectives.
"Investigation of things means rectifying what is incorrect in the mind."
Again affirming the definition of investigation — not exhaustively studying external principles, but correcting the incorrectness of the inner mind. This is consistent with the definition "to investigate is to rectify" in §11.