“All things the world which fill of but one stuff are spun.” Out of that stuff, minds also are formed; and, in its inner reality, it is itself of the nature of mind. This is essentially the metaphysical doctrine set forth by Clifford in his essay “On the Nature of Things-in-themselves.” “Mind-stuff” is not, as some critics have supposed, “a substance combining physical and psychical properties.” Matter, according to Clifford, is purely a phenomenon. The external world is a kind of “dream” of each of us. Our dreams of this kind resemble one another in certain respects; hence we are able to use a common language about them. Corresponding to the “dream,” or phenomenon, is an inner reality. In our own minds we know a portion of this reality. The reality of the individual mind corresponds to the phenomenon we call the body. To animal bodies correspond minds more or less resembling ours. To inorganic things correspond elements of “mind-stuff” not ordered in such a way as to enter into a consciousness. Consciousness depends on the assumption of form by elements of mind-stuff; and, though all elements of mind-stuff have the possibility of assuming the form of consciousness, not all have actually attained that form. The entirely unformed elements, though in themselves of mental nature, must be called unconscious.