As I’ve been arguing in previous posts, Leibniz in 1686 offered an argument that [A] all individual substances express God. As he put the point in the essay “Primary Truths”, “all individual created substances are different expressions of the same universe and different expressions of the same universal cause, namely God” (my italics).
However Leibniz also said, towards the end of the “Discourse on Metaphysics”, that [B] “other substances express the world rather than God, while minds express God rather than the world” (DM 36). Something very similar is in the summary of DM35, and in at least two of Leibniz’s letters to Arnauld (A 2.2.60, 2.2.257). This appears to be in contradiction with [A]. It held that all individual substances express God, whereas this appears to be the view that only some individual substances, minds, express God.
The last four sections of the “Discourse” (34-7) are focused on the distinction between minds and other substances. Even here Leibniz continues to suggest, in places, that all substances express God. Thus in DM 35 we are told that “the whole nature, end, virtue, and function of substance is merely to express God and the universe”. But DM 36 (and indeed the summary of 35) appear to deny that all substances express God.
Setting aside for the moment the question of how Leibniz can claim both [A] and [B], what is it that leads him to assert [B]?
One might try (here’s me trying) to say that [B] is not to be taken literally, saying there’s not really a difference between what minds and other substances express, though there are related differences (about, e.g., whether this expression is accompanied by knowledge). Thus [B] would just be a misleading summary of that point. But, if nothing else, Leibniz says [B] repeatedly, and not just in a section summary, so this looks rather weak. What else might one say here?
Well, one theme in the discussion is that minds are made in God’s image, in such a way that a mind “does not merely express the world but it also knows it and it governs itself after the fashion of God”. So minds have a sort of resemblance to God that the other substance lack. And for this reason we might say that minds express God, whereas other substances do not. (Many thanks here to Julia Jorati for her thoughts about these passages, especially this aspect of them.)
Back to the question of how this all fits together. One might reconcile [A] and [B] by saying that minds express God in two ways and for two reasons (because he is their cause, and because they resemble him by having intellect and will) but other substances only express him in one way (because he is their cause). But this still doesn’t fit terribly well with the claim that substances other than minds express the world rather than God.
Thinking about it in this way, there look to me to be two views about expression of God in the “Discourse”: the view seen in the later sections, on which minds resemble and thus express God, but other substances don’t do that so well, and merely represent the world; and the one of the earlier sections, on which both sorts of substance express both God and the world. I’m inclined to take this as evidence for something like Catherine Wilson’s reading of the “Discourse” as containing multiple systems that don’t fit perfectly well together.