is virtual or real, perception and sensation are characterized and distinguished, he becomes unable to find any other difference between them than a difference of degree. Then, profiting by the fact that affective sensation is but vaguely localized (because the effort it involves is an indistinct effort) at once he declares it to be unextended; and these attenuated affections or unextended sensations he sets up as the material with which we are supposed to build up images in space. Thereby he condemns himself to an impossibility of explaining either whence arise the elements of consciousness, or sensations, which he sets up as so many absolutes, or how, unextended, they find their way to space and are coordinated there, or why, in it, they adopt a particular order rather than any other, or, finally, how they manage to make up an experience which is regular and common to all men. This experience, the necessary field of our activity, is, on the contrary, what we should start from. Pure perceptions, therefore, or images, are what we should posit at the outset. And sensations, far from being the materials from which the image is wrought, will then appear as the impurity which is introduced into it, being that part of our own body which we project into all others.
V. But, as long as we confine ourselves to sensation and to pure perception, we can hardly be said to be dealing with the spirit. No doubt we demonstrate, as against the theory of an
