 The analogy with thought hardly emphasises the independence of substance! Nevertheless, created substances do constitute the created world, and do, in that sense, meet criterion (i) for being substance. They are also the subjects of predication, so they meet criterion (iii). Leibniz’s substances, however, are the bearers of change (criterion (iv)) in a very different way from Aristotle’s individual substances. An Aristotelian individual possesses some properties essentially and some accidentally. The accidental properties of an object are ones that can be gained and lost over time, and which it might never have possessed at all: its essential properties are the only ones it had to possess and which it possesses throughout its existence. The situation is different for Leibniz’s monads—which is the name he gives to individual substances, created or uncreated (so God is a monad). Whereas, for Aristotle, the properties that an object has to possess and those that it possesses throughout its existence coincide, they do not do so for Leibniz. That is, for Leibniz, even the properties that an object possesses only for a part of its existence are essential to it. Every monad bears each of its properties as part of its nature, so if it were to have been different in any respect, it would have been a different entity.