  Aristotle’s views on the persistence of things are worth noting here. At the risk of gross oversimplification of what is treated thoroughly elsewhere (see the entry on   Aristotle’s metaphysics, it can be said that early on he took the view that what persists over time and through change, the substrate, can be identified with matter, and that it is the form of matter which is acquired or lost (Physics I, 5–7). When he wrote the Categories, it is substance which is said to be susceptible of contrary attributions; and as such substance itself has no opposites. (Categories 4a10). In the Metaphysics \(Z\), a more complex doctrine of substance, that which \(is\), is worked out. Substance is not the substrate, matter, since that lacks particularity. Its substance, what it is to be that thing, that without which it does not exist, is its essence. Aristotle then links essence with his theory of causes, being identified variously with its final cause and with its formal cause. 