 While Descartes’s “first philosophy” clearly defends dualism, he takes his target to be skepticism rather than idealism, and thus is from our point of view concerned to resist the adoption of epistemological grounds; Spinoza is often though controversially thought to defend a form of materialism, but takes his primary target to be pluralism as contrasted to monism; and Leibniz does not seem overly worried about choosing between idealist and dualist forms of his “monadology”, while his famous thesis that each monad represents the entire universe from its own point of view might be taken to be a form of epistemological ground for idealism, but Leibniz does not seem to conceive of it as such. Nicolas Malebranche’s theory of “seeing all things in God” might be the closest we find to an explicit assertion in seventeenth-century philosophy of an argument for idealism on both epistemological and ontological grounds, and thus as a forerunner of the “absolute” idealism of the nineteenth century. While from a later point of view it may seem surprising that these rationalists were not more concerned with explicitly asserting or refuting one or both versions of idealism, perhaps they were more concerned with theological puzzles about the nature and essence of God, metaphysical questions as to how to reconcile the respective conception of God with views about the interaction of substances of fundamentally different kinds, and epistemological problems as to the possibility of knowledge and cognitive certainty than they were worried about whether the ultimate constituents of reality were mental or material elements.