projecting into it memories more or less remote. But such is not the usual way of describing the process. Sometimes the mind is supposed to be absolutely independent of circumstances, to work exactly as it likes on present or absent objects;—and then we can no longer understand how it is that the normal process of attention may be seriously impaired by even a slight disturbance of the sensori-motor equilibrium. Sometimes, on the contrary, the evocation of images is supposed to be a mere mechanical effect of present perception; it is assumed that, by a necessary concatenation of processes, supposed to be all alike, the object calls forth sensations and the sensations ideas which cling to them;—but then, since there is no reason why the operation, which is mechanical to begin with, should change its character as it goes on, we are led to the hypothesis of a brain wherein mental states may dwell to slumber and to awaken. In both cases the true function of the body is misunderstood, and as neither theory teaches how and why the intervention of a mechanism is necessary, neither of them is able to show where such intervention should stop if it is once brought in.
But it is time to leave these general considerations. We must ascertain whether our hypothesis is confirmed or contradicted by the facts of cerebral localization known at the present day. The disorders of imaginative memory, which correspond to local lesions of the cortex, are
