 Matter, Kant could readily agree with Leibniz, cannot be a thing in itself, stuff possessed of characteristics and qualities independent of human perception; what we call matter is an appearance (4:507). The true nature of mind-independent external reality cannot be described by reference to shape, contact or movement, which characterize only the objects presented to us (A265–6/B 321–2). He understood Leibniz’s reasoning in favour of monads as follows: It is impossible to conceive two material atoms as both different from one another and as simple, i.e partless; yet possible to conceive two souls that are both different and partless (20:285). Therefore, if substances are manifold and partless, they must have representational capacities. The crucial error in this reasoning lay in supposing that our abstract conceptions are a guide to reality behind the spatio-temporal appearances. Yet properly understood, he maintained, Leibniz’s monadology was not an attempt to explain appearances but the expression of a “Platonic” view of the world, considered apart from our sensory experience of it (4:507; 8:248). In this regard, he did grasp that Leibniz did not after all take appearances for things in themselves.