this is why, when we really wish to know a thing, we are obliged to learn it by heart, that is to say, to substitute for the spontaneous image a motor mechanism which can serve in its stead. But there is a certain effort sui generis which permits us to retain the image itself, for a limited time, within the field of our consciousness; and, thanks to this faculty, we have no need to await at the hands of chance the accidental repetition of the same situations, in order to organize into a habit concomitant movements; we make use of the fugitive image to construct a stable mechanism which takes its place.—Either, then, our distinction of the two independent memories is unsound, or, if it corresponds to facts, we shall find an exaltation of spontaneous memory in most cases where the sensori-motor equilibrium of the nervous system is disturbed; an inhibition, on the contrary, in the normal state, of all spontaneous recollections which do not serve to consolidate the present equilibrium; and lastly, in the operation by means of which we acquire the habit-memory, a latent intervention of the image-memory. Let us see whether the facts confirm this hypothesis.
For the moment we will insist on neither point; we hope to throw ample light upon both when we study the disturbances of memory and the laws of the association of ideas. We shall be content for the present to show, in regard to things which are learnt, how the two memories run side by side and lend to each other a mutual support. It is
