Since matter is in itself nothing, a bare unrealised capacity, while form is actuality, the completed and perfected being, it follows that form is something higher than matter. But matter is what becomes form. In order of time, therefore, matter is earlier, form later. But in order of thought, and in reality, it is otherwise. For when we say that matter is the potentiality of what it is to become, this implies that what it is to become is already present in it ideally and potentially, though not actually. The end, therefore, is already present in the beginning. The oak is in the acorn, ideally, otherwise the oak could never come out of it. And since all becoming is towards the end, and would not take place but for the end, the end is the operative principle and true cause of becoming. Motion is produced not by a mechanical propulsive force, pushing from behind, so to speak, but by an ideal attractive force, drawing the thing towards its end, as a piece of iron is drawn to the magnet. It is the end itself which exerts this force. And, therefore, the end must be present at the beginning, for if it were not present it could exert no force. Nay, more. It is not only present in the beginning, it is anterior to it. For the end is the cause of the motion, and the cause is logically prior to its consequence. The end, or the principle of form, is thus the absolute first in thought and reality, though it may be the last in time. If, then, {281} we ask what, for Aristotle, is that ultimate reality, that first principle, from which the entire universe flows, the answer is, the end, the principle of form. And as form is the universal, the Idea, we see that his fundamental thesis is the same as Plato's. It is the one thesis of all idealism, namely, that thought, the universal, reason, is the absolute being, the foundation of the world. Where he differs from Plato is in denying that form has any existence apart from the matter in which it exhibits itself.