In part II of his Ethics, Spinoza offers some striking reflections on the mind’s relation to the body, two aspects of which I’ll note here. First, he defines the body (corpus) as “Obiectum ideae humanam mentem constituentis” (the object of the idea constituting the human mind) (2p13). There’s an interesting anticipation here of the Kantian notion that a person isn’t one object among others, but a particular vantage on the world of objects — the body is just the object of the (congeries of?) idea(s) which the mind is (and so again, possibly a nod in the direction of Hume’s decompositional approach to mind). The subject/object language is striking too in the way it implies a certain order of priority — this isn’t a mere correlation of mind and world as could be suggested by, for instance, Ethics 2p7, but rather a claim that the body subsists as the object corresponding to the mind’s ideas. He makes this “idealizing” tendency still clearer in the corollary he deduces from this proposition: “Hinc sequitur hominem mente et corpore constare, et corpus humanum, prout ipsum sentimus, existere” (It follows that the human consists in mind and in body, and that the human body, insofar as we sense it, exists) (2p13c).
And things get more interesting yet when he offers a scholium on this proposition, in which he notes, “omnia, quamvis diversis gradibus, animata tamen sunt” (all things, although in diverse grades, are animate) (2p13s). This is amazingly close to the teaching of Spinoza’s contemporary and friend-rival, Leibniz, who wrote, “there is a world of creatures, of living things, of animals, of entelechies, of souls in the least part of matter” (Monadology, Sec. 66). The two spent a few propitious days together at Spinoza’s home in the Hague in November 1676, when Leibniz was 30, and Spinoza, though only in his mid-40’s, was just months away from death. Leibniz seems to have read a manuscript copy of what would become the Ethics at this point; it’s hard to imagine that the Monadology wasn’t his attempt to inscribe Spinoza’s genuine insights into a more classical and faithfully Christian (or indeed, simply theistic) framework.