the world, including matter, arises out of that prime being. Either matter arises out of form or it does not. If it does, this arising must be exhibited. If it does not, then form is not the sole ultimate reality, for matter is equally an ultimate, underivative, {335} primordial substance. In that case, we thus have two equally real ultimate beings, each underived from the other, existing side by side from all eternity. This is dualism, and this is the defect of Aristotle. Not only does he not derive matter from form, but he obviously sees no necessity for doing so. He would probably have protested against any attempt to do so, for, when he identifies the formal, final, and efficient causes with each other, leaving out the material cause, this is equivalent to an assertion that matter cannot be reduced to form. Thus his dualism is deliberate and persistent. The world, says Aristotle, is composed of matter and form. Where does this matter come from? As it does not, in his system, arise out of form, we can only conclude that its being is wholly in itself, i.e., that it is a substance, an absolute reality. And this is utterly inconsistent with Aristotle's assertion that it is in itself nothing but a mere potentiality. Thus, in the last resort, this dualism of sense and thought, of matter and Idea, of unlimited and limiting, which runs, "the little rift within the lute," through all Greek philosophy, is not resolved. The world is not explained, because it is not derived from a single principle. If form be the Absolute, the whole world must flow out of it. In Aristotle's system, it does not.