GB:
问∶天地之心，天地之理，理是道理，心是主宰底意否？ 曰∶ 心固是主宰底意，然所谓主宰者即是理也。不是心外别有个理， 理外别有个心。又问∶此心字与帝字相似否？曰∶人字似天字， 心字似帝字。
big5:
拜ぱぇみぱぇ瞶瞶琌笵瞶み琌甠┏種 り み㏕琌甠┏種礛┮孔甠琌瞶ぃ琌みΤ瞶 瞶Τみ拜み籔りぱ み
[Someone] asked: "As for the heart/mind of Heaven and Earth, and as for the li of Heaven and Earth, does 'li' mean 'dao-li' (reason or rationale for doing something), and does heart/mind refer to autonomy (or will)? [Zhu Xi] replied: "Heart/mind does indeed refer to autonomy, however what we would speak of as the wielder of this autonomy is the li. It is not as though outside of the heart/mind there is somewhere else a li, or that outside of the li there would be a heart/mind." [The questioner] asked further: "Is this word 'heart/mind' analogous to the word 'ruler'?" [Zhu Xi] replied: "The word 'human being' is analogous to 'Heaven', and the word 'heart/mind' is analogous to 'ruler'."
Commentary:
This conversation opens an area that has not been discussed before, the relation between the heart/mind of an ordinary human being and the heart/mind of Heaven and Earth.
Heaven and Earth have a heart/mind whose function is the autonomous practice of willing and decision making, but it is not a "material" thing, not a thing composed of qi. Heaven is analogous to a human being, and the human heart/mind is analogous to the ruling function that guides the world. (By the end of this passage, Earth has been omitted from the discussion.)
In the case of what we in the West would call the material things of this world, to each entity there is both a lifebreath (material) aspect and a li (formal) aspect. So a human heart/mind has a lifebreath aspect, the physical heart (or brain, according to Western belief), and a li or formal aspect. The li aspect is the aspect that determines why one wills and decides as one does. The hearts and brains of humans and cows are similar in gross appearance, but the motivations of humans and cows differ in important respects, and these differences can be accounted for as differences in li.
Heaven does not have a palpable lifebreath aspect. If we look at the most direct manifestation of Heaven in our daily lives, the clear blue sky of the daytime and the clear black sky of the night, we find no building blocks, no texture, no indication that there is really anything there at all. Perhaps it is just space, and space is no real thing, just the absence of being. In that case, Heaven (or space) would have no characteristics or properties. But when we observe the sky and ask what takes place in it, we see that the sun moves in a predictable way that changes from day to day, that the stars in the night time sky also hold regular positions with regard to each other and also move slowly across the nighttime sky in a way that, miraculously, coordinates exactly with the seasons. The moon moves and changes phases in ways that coordinate quite obviously with earthly activities such as the changes in the tides. Five of the stars are not still in respect to each other and to the other stars, and these five "travelling stars" (planets) trace out intricate paths across the vastness of the nighttime sky without dependence on any signposts or any interference from men or from other visible entities. So it appears that the li of Heaven may refer to the extremely consistent behaviors of the sun, moon, planets, stars, etc.
If we think of the "dao-li" mentioned above as a colloquial expression meaning something like "the way things work," or "an understanding of the way things work," or "the reason that things work they way they do," then Zhu Xi affirms that the reason that things work the way they do is the same as the "ruler" or the "will" function of Heaven. So he affirms that Heaven determines, e.g., the paths followed by the planets. It does so by its very nature, not by virtue of any separate act of will or desire.
I am not sure whether this passage is generally consistent with Zhu Xi's other pronouncements on this topic, but it does compare nicely with Zhu's general position on human volition. Humans have a heart/mind that has a qi aspect and a li aspect. They are also said to have a ren2 xin1 (human mind) and a dao4 xin1 (mind that transcends human passions and desires). Possibly the dao4 xin1 is viewed as a shared version of the heart/mind of Heaven.
--PEM