来教谓：「如必以学不资于外求，但当反观、内省以为务，则『正心诚意』四字亦何不尽之有？何必于入门之际，便困以『格物』一段工夫也？」诚然诚然！若语其要，则「修身」二字亦足矣，何必又言「正心」？「正心」二字亦足矣，何必又言「诚意」？「诚意」二字亦足矣，何必又言「致知」、又言「格物」？惟其工夫之详密，而要之只是一事；此所以为「精一」之学，此正不可不思者也。夫理无内外，性无内外，故学无内外。讲习、讨论，未尝非内也；反观、内省，未尝遗外也。夫谓学必资于外求，是以己性为有外也，是「义外」也，用智者也；谓反观、内省为求之于内，是以己性为有内也，是有我也，自私者也；是皆不知性之无内外也。故曰：「精义入神，以致用也；利用安身，以崇德也。」「性之德也，合内外之道也。」此可以知「格物」之学矣。「格物」者，《大学》之实下手处，彻首彻尾，自始学至圣人，只此工夫而已。非但入门之际有此一段也。夫「正心」、「诚意」、「致知」、「格物」，皆所以「修身」，而「格物」者，其所用力，日[1]可见之地。故「格物」者，格其心之物也，格其意之物也，格其知之物也；「正心」者，正其物之心也；「诚意」者，诚其物之意也；「致知」者，致其物之知也。此岂有内外、彼此之分哉？理一而已，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」。正者，正此也；诚者，诚此也；致者，致此也；格者，格此也，皆所谓穷理以尽性也。天下无性外之理，无性外之物。学之不明，皆由世之儒者认理为外，认物为外；而不知「义外」之说，孟子盖尝辟之，乃至袭陷其内而不觉，岂非亦有似是而难明者欤？不可以不察也！
来信说：「如果学问一定不借助外求，只应当以反观内省为务，那么『正心诚意』四个字还有什么不尽的？何必在入门之际，就用『格物』一段功夫困住人呢？」诚然诚然！若论要领，「修身」二字也够了，何必又说「正心」？「正心」二字也够了，何必又说「诚意」？「诚意」二字也够了，何必又说「致知」、又说「格物」？正因为功夫详密，而归结起来只是一事，这才是「精一」之学，这正是不可不思考的。理无内外，性无内外，所以学无内外。讲习讨论未尝不是内；反观内省未尝遗外。说学必须资于外求，那是认为自己性有外，是「义外」，是用智；说反观内省是求之于内，那是认为自己性有内，是有我，是自私。这都是不知道性无内外。所以说：「精义入神，以致用也；利用安身，以崇德也。」「性之德也，合内外之道也。」由此可以知「格物」之学了。「格物」是《大学》实际下手处，彻首彻尾，从初学到圣人，只是这一个功夫而已，并非只在入门之际有这一段。「正心」「诚意」「致知」「格物」都是用来「修身」的，而「格物」是其所用之力、天天可见的地方。所以「格物」，是格其心之物、格其意之物、格其知之物；「正心」，是正其物之心；「诚意」，是诚其物之意；「致知」，是致其物之知。这哪里有内外彼此之分呢？理只是一个：就理的凝聚而言叫作「性」，就凝聚的主宰而言叫作「心」，就主宰的发动而言叫作「意」，就发动的明觉而言叫作「知」，就明觉的感应而言叫作「物」。所以就近处说，谓之「格」；就知说，谓之「致」；就意说，谓之「诚」；就心说，谓之「正」。正，是正这个；诚，是诚这个；致，是致这个；格，是格这个，都是所谓穷理以尽性。天下没有性外之理，没有性外之物。学之不明，都由于世上儒者认理为外、认物为外，而不知道「义外」之说孟子早已驳斥过，竟然沿袭陷入其中而不自觉，岂不也是似是而难明吗？不可不察啊！
Your letter says: 'If learning needs nothing from outside and must only turn inward and examine within, what do the four words rectify the mind and make the intention sincere fail to cover? Why plague the beginner at the gate with a stretch of investigating things?' Indeed, indeed! For the essential, self-cultivation alone suffices — why add rectifying the mind? Rectifying suffices — why add sincerity? Sincerity suffices — why add extension, add investigation? Just because the work is laid out in detail while summing to one affair — this is the learning of refinement and unity, and this is what must be pondered. Principle has no inner or outer, nature no inner or outer, hence learning none. Lecture and discussion are not thereby not-inner; reflection and self-examination do not thereby drop the outer. To say learning must draw from without makes one's nature have an outside — rightness-external, wit in selfishness. To say turning inward is seeking within makes one's nature have an inside — self-assertion, selfishness. Both know not that nature has no inner or outer. Hence: refine the meaning to enter the spirit, thence to apply; use the applied to secure the self, thence to exalt virtue — virtue of nature, the way joining inner and outer. From this the learning of investigating things may be known. Investigating things is where the Great Learning actually lays hands: from first to last, from beginner to sage, this work only — not a stretch merely at the gate. Rectifying, sincerity, extension, investigation all serve self-cultivation, and investigation is where the applied strength is daily visible. Thus investigating things is correcting the mind's things, the intention's things, the knowledge's things; rectifying the mind is rectifying the mind of things; sincerity is making the intention toward things sincere; extension is extending the knowledge of things. Where is inner or outer, this or that in it? Principle is one: as congealed it is called nature; as the master of the congealing, mind; as the master's stirring, intention; as the stirring's bright awareness, knowledge; as the awareness's responding, thing. Spoken of at the thing, correcting; at the knowledge, extending; at the intention, making sincere; at the mind, rectifying. Rectify this; make sincere this; extend this; correct this — all of it exhausting principle to fulfill nature. Under heaven there is no principle outside nature, no thing outside nature. That learning is dark comes of scholars taking principle as outer and thing as outer, forgetting Mencius long ago condemned rightness-external — falling heir to the pit unaware. Is that not also plausible-yet-false and hard to see? It cannot go unexamined!
- 「日」字，施本、俞本并作「实」。