becoming, and provide our activity with points to which it can be applied.
But erroneous conceptions about sensible quality and about space are so deeply rooted in the mindQualities of different orders share in extensity, though in different degrees. that it is important to attack them from every side. We may say then, to reveal yet another aspect, that they imply this double postulate, accepted equally by realism and by idealism: first, that between different kinds of qualities there is nothing common; second, that neither is there anything common between extensity and pure quality. We maintain, on the contrary, that there is something common between qualities of different orders, that they all share in extensity, though in different degrees, and that it is impossible to overlook these two truths without entangling in a thousand difficulties the metaphysic of matter, the psychology of perception and, more generally, the problem of the relation of consciousness with matter. Without insisting on these consequences, let us content ourselves for the moment with showing, at the bottom of the various theories of matter, the two postulates which we dispute and the illusion from which they proceed.
The essence of English idealism is to regard extensity as a property of tactile perceptions. As it sees nothing in sensible qualities but sensations, and in sensations themselves nothing but mental states, it finds in the different qualities
