senses are opened to them, unperceived when they are closed. ... Now of
these images there is ONE which is distinct from all the others, in that
I do not know it only from without by perceptions, but from within by
affections; it is my body."[Footnote: Matter and Memory, p. 1 (Fr. p.
1).] Further examination shows me that these affections "always
interpose themselves between the excitations from without and the
movement which I am about to execute."[Footnote: Matter and Memory, p. 1
(Fr. p. 1).] Indeed all seems to take place as if, in this aggregate of
images which I call the universe, nothing really new could happen except
through the medium of certain particular images, the type of which is
furnished me by my body."[Footnote: Matter and Memory, p. 3 (Fr. p. 2).]
Reference to physiology shows in the structure of human bodies afferent
nerves which transmit a disturbance to nerve centres, and also efferent
nerves which conduct from other centres movement to the periphery, thus
setting in motion the body in whole or in part. When we make enquiries
from the physiologist or the psychologist with regard to the origin of
these images and representations, we are sometimes told that, as the
centrifugal movements of the nervous system can evoke movement of the
body, so the centripetal movements--at least some of them--give rise to
the representation, mental picture, or perception of the external world.
Yet we must remember that the brain, the nerves, and the disturbance of
the nerves are, after all, only images among others. So it is absurd to
state that one image, say the brain, begets the others, for "the brain
is part of the material world, but the material world is not part of the
brain. Eliminate the image which bears the name 'material world,' and
you destroy, at the same time, the brain and the cerebral disturbances
which are parts of it. Suppose, on the contrary, that these two images,
the brain and the cerebral disturbance, vanish; ex hypothesi you efface
only these, that is to say, very little--an insignificant detail from an
immense picture--the picture in its totality, that is to say, the whole