Li Lou II · Passage 26 / 33 · 孟子 4B.26
Mencius 4B.26: to speak of nature is to follow what is so
Mencius argues that speaking about nature must follow the thing's own pattern, not arbitrary carving. True intelligence is like Yu's management of water.
孟子曰：「天下之言性也，則故而已矣。故者，以利為本。所惡於智者，為其鑿也。如智者，若禹之行水也，則無惡於智矣。禹之行水也，行其所無事也。如智者亦行其所無事，則智亦大矣。天之高也，星辰之遠也，茍求其故，千歲之日至，可坐而致也。」
Mencius said, 'All who speak about the natures of things, have in fact only their phenomena to reason from, and the value of a phenomenon is in its being natural. What I dislike in your wise men is their boring out their conclusions. If those wise men would only act as Yu did when he conveyed away the waters, there would be nothing to dislike in their wisdom. The manner in which Yu conveyed away the waters was by doing what gave him no trouble. If your wise men would also do that which gave them no trouble, their knowledge would also be great. There is heaven so high; there are the stars so distant. If we have investigated their phenomena, we may, while sitting in our places, go back to the solstice of a thousand years ago.'
Priority note
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Central question
Why does Mencius say that all talk of nature must come down to what is naturally so, and compare true intelligence to Yu's handling of water?
Direct answer
Because he is resisting two failures at once: empty speculation detached from the thing itself, and cleverness that forces reality into a human design. To speak of nature is to follow the object's own order, and true intelligence completes that order instead of violating it.
First principle
Good judgment does not coerce reality into a preferred model. It first finds the logic already present in the thing and then works with it.
Why it matters
This passage serves searches around nature, method, Yu and water, and Mencius on what disciplined reasoning about human nature should look like.
Further reading
What this passage is doing
This is passage 26 of 33 in Li Lou II. The cleanest entry point is "All who speak about the natures of things,…". In context, it works as part of Mencius's argument about seeing people clearly, ritual restraint, and governing relationships and can be read alongside Human nature, Humane government / kingly way.
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Related principles
Citation note
Do not reduce it to a slogan for empiricism. Mencius is not abolishing theory; he is insisting that theory be answerable to the thing's own pattern, or else intelligence turns into distortion.