knowledge of the external world, have here their origin. Many
philosophers and psychologists "show us a brain, analogous in its
essence to the rest of the material universe, consequently an image, if
the universe is an image. Then, since they want the internal movements
of this brain to create or determine the representation of the whole
material world--an image infinitely greater than that of the cerebral
vibrations--they maintain that these molecular movements, and movement
in general, are not images like others, but something which is either
more or less than an image--in any case is of another nature than an
image--and from which representation will issue as by a miracle. Thus
matter is made into something radically different from representation,
something of which, consequently, we have no image; over against it they
place a consciousness empty of images, of which we are unable to form
any idea. Lastly, to fill consciousness, they invent an incomprehensible
action of this formless matter upon this matterless thought."[Footnote:
Matter and Memory, p. 9 (Fr. pp. 7-8).]

The problem at issue between Realists and Idealists turns on the fact
that there are two systems of images in existence. "Here is a system of
images which I term 'my perception of the universe,' and which may be
entirely altered by a very slight change in the privileged image--my
body. This image occupies the centre. By it all the others are
conditioned; at each of its movements everything changes as though by a
turn of a kaleidoscope. Here, on the other hand, are the same images,
but referred each one to itself, influencing each other no doubt, but in
such a manner that the effect is always in proportion to the cause; this
is what I term the 'universe.'"[Footnote: Matter and Memory, p. 12 (Fr.
p. 10).] The question is, "How is it that the same images can belong at
the same time to two different systems--the one in which each image
varies for itself and in the well-defined measure that it is patient of