between the physical object and the object of cognition contained in every sensation. The line of demarcation between the physical and the moral cannot pass this way, since it would separate facts which are identical.
We can, therefore, only deplore the error of all those who, to express the difference between mind and matter, have sought a contrast between sensation and physical facts. Physiologists, with hardly an exception, have fallen into this error; when contemplating in imagination the material working of the brain, they have thought that between the movement of cerebral matter and sensation there was a gulf fixed. The comparison, to have been correct, required to be presented in quite another way. A parallel, for instance, should have been drawn between a certain cerebral movement and the act of consciousness, and there should have been said: “The cerebral motion is the physical phenomenon, the act of consciousness the psychical.” But this distinction has not been made. It is sensation en bloc which is compared to the cerebral movement, as witness a few passages I will quote as a matter of curiosity, which are borrowed from philosophers and, especially, from physiologists.
While philosophers take as a principle of idealism, that the mental can only know the mental, physiologists take, as a like principle,
