Page:Popular Science Monthly Volume 5.djvu/731

Rh The warning against these experiments, which are too much the pastime of the idle, the hysterical, and the foolish, is of weighty import:

The question of "Unconscious Cerebration" or "Latent Mental Modification," which is peculiarly Dr. Carpenter's own, is too important and unsettled to be fully discussed within the brief limits of a review. Dr. Carpenter thinks that his views had been anticipated by Sir William Hamilton, but the passage he quotes from that philosopher scarcely appears to us to detract from the author's priority of thought. Sir W. Hamilton's "mental activities and passivities of which we are unconscious, but which manifest their existence by effects of which we are conscious," are plainly indicated by the sentence which follows as referring to the unknown and the incognizable. We are conscious of the knowable, unconscious of the unknowable.

Hamilton proceeds to explain that we can only be conscious of a determinate state or mental condition which supposes a transition from some other state: "But as the modification must be present before we have a consciousness of it, we can have no consciousness of its rise or awakening, for this is also the rise or awakening of consciousness."

If all this means, any thing, it must mean that we are only conscious of mental states which exist at the time, and that we are unconscious of preceding mental states, or of the transition from preceding to existing states. How Dr. Carpenter can hatch unconscious cerebration out of that egg we cannot imagine.

Neither can we see how John S. Mill can be thought "explicitly to accept the doctrine of unconscious cerebration," seeing that he "considers unconscious mental modification as a contradiction in terms; attributing the phenomena to unrecognized changes in the substance of the brain which he regards as the constant physical attendants of mental modifications."

No doubt there are many brain-changes of which we are not conscious, but mental change, without consciousness, is, according to this