to indicating the degree of indetermination allowed to the acts of the special image which you call your body. And, inversely, it follows that the indetermination of the movements of your body, such as it results from the structure of the grey matter of the brain, gives the exact measure of the extent of your perception. It is no wonder, then, that everything happens as though your perception were a result of the internal motions of the brain, and issued in some sort from the cortical centres. It could not actually come from them, since the brain is an image like others, enveloped in the mass of other images, and it would be absurd that the container should issue from the content. But since the structure of the brain is like the detailed plan of the movements among which you have the choice, and since that part of the external images which appears to return upon itself in order to constitute perception includes precisely all the points of the universe which these movements could affect, conscious perception and cerebral movement are in strict correspondence. The reciprocal dependence of these two terms is therefore simply due to the fact that both are functions of a third, which is the indetermination of the will.
Take, for example, a luminous point P, of which the rays impinge on the different partsThe image, then, is formed and perceived in the object, not in the brain. a, b, c, of the retina. At this point P science localizes vibrations of a certain, amplitude and duration. At the
