of 'pure recollection,' that there is not between recollection and perception a mere difference of degree but a radical difference of kind.
VII. Let us point out to begin with the metaphysical, and no longer merely psychological,The different planes of consciousness. bearing of this last problem. No doubt we have a thesis of pure psychology in a proposition such as this: recollection is a weakened perception. But let there be no mistake: if recollection is only a weakened perception, inversely perception must be something like an intenser memory. Now the germ of English idealism is to be found here. This idealism consists in finding only a difference of degree, and not of kind, between the reality of the object perceived and the ideality of the object conceived. And the belief that we construct matter from our interior states and that perception is only a true hallucination, also arises from this thesis. It is this belief that we have always combated whenever we have treated of matter. Either, then, our conception of matter is false, or memory is radically distinct from perception.
We have thus transposed a metaphysical problem so as to make it coincide with a psychological problem which direct observation is able to solve. How does psychology solve it? If the memory of a perception were but this perception weakened, it might happen to us, for instance, to take the perception of a slight sound for the recol-
