emits, the retina and the nervous elements affected, form a single whole; that the luminous point P is a part of this whole; and that it is really in P, and not elsewhere, that the image of P is formed and perceived.
When we represent things to ourselves in this manner, we do but return to the simple convictions of common sense. We all of us began by believing that we grasped the very object, that we perceived it in itself and not in us. When philosophers disdain an idea so simple and so close to reality, it is because the intra-cerebral process,—that diminutive part of perception,—appears to them the equivalent of the whole of perception. If we suppress the object perceived and keep the internal process, it seems to them that the image of the object remains. And their belief is easily explained: there are many conditions, such as hallucination and dreams, in which images arise that resemble external perception in all their details. As, in such cases, the object has disappeared while the brain persists, he holds that the cerebral phenomenon is sufficient for the production of the image. But it must not be forgotten that in all psychical states of this kind memory plays the chief part. Now, we shall try to show later that, when perception, as we understand it, is once admitted, memory must arise, and that this memory has not, any more than perception itself, a cerebral state as its true and complete condition. But, without as yet enter-
