We are thus led to the conclusion that there are in the phenomena of memory, taken as a whole, certain peculiarities, by virtue of which this memory is more or less vivid in such or such an individual as regards such or such a cerebral operation, and that thus there are a certain number of local memories very clearly deter mined, each having, in a manner, an autonomy as inde pendent as the generating sensorial impressions with which it is intimately associated.
Association of Memories.—The study of the brain has shown us that there are isolated regions designed to receive and elaborate independently isolated groups of sensorial impressions. The study of the cortex, on the other hand, has shown us that if there be a certain functional autonomy, as regards the dispersion of im pressions, this autonomy is neither complete nor defini tive, seeing that examination of the nervous tissue of the cortex, proves that this tissue forms a continuous whole throughout all its extent, a unity as complete as that of the cutaneous surface—so that the excitations perceived at a given moment, in a certain region of the sensorium, are nevertheless liable to be disseminated at a distance, and to associate the different regions of the cerebral tissue in their vibration. (Figs. I and 6.) Thus, for instance, when, in the presence of a picture, a landscape, or any object which may catch our eye, the special regions of our brain which elaborate optic impressions are thrown into activity, it is only homo geneous optic impressions, and nothing but optic im pressions, which are active in a determinate region of the cortex.
When, on the other hand, my view extends over a landscape, or over a flower-bed balmy with fragrant emanations ; when I am present at a theatrical repre sentation in which the splendours of the anise en scene equal the magnificence of the musical harmony, my brain is no longer excited by a homogeneous stimulus ; it is assailed by a series of simultaneous impressions which come in a crowd and impress themselves all at once upon the sensorium.
These simultaneous impressions—optic, olfactive, acoustic, received at the same moment, and in several circumscribed localities at the same time, constitute a series of contemporaneous souvenirs which are created and implanted in me ; and, henceforth, those vibrations which were born together, and were simultaneously conceived, will represent, in the general series of my reminiscences, a definite group, of which the elements, united by the bonds of a mysterious federation, will all live with the same life, anastomose one with another, and recall one another as soon as one link of the chain is struck.
Thus it is that the sight of even a corner of the landscape I first saw, or of the flower-bed that grati fied my sense of smell, will recall to me the odour of the plants that I had pleasure in smelling, and even the emotions that I experienced at that very moment ; and inversely, these perfumes accidentally inhaled at a later period, will evoke in me automatically a reminiscence of the place, the flower-bed, where they were simulta neously inhaled. Thus it is, again, that the sight of such or such a theatrical decoration will remind me of t he piece of music heard in its presence, and that, in the same way, if under other circumstances I hear the trains that have impressed me, I shall feel awakened within me reminiscences connected with it, which will represent to me the decorations and the ocular spec tacle in the presence of which I heard the musical sounds for the first time.
By taking more and more complex examples, we find that in the ordinary phenomena of cerebral activity, not merely are binary, ternary, or quaternary groups of sensorial impressions juxtaposed and imprinted upon the sensorium, but many multiple agglomerations are created within us and proceed from all the sensibilities of the organism successively and simultaneously laid under contribution.
Thus the pleasures of gastronomy may easily be allied, as Brillat-Savarin has so well explained, with all other pleasures ; the seductions of physical pleasure, which are the synthesis of all the sensibilities of the organism in agitation, leave in the sensorium traces all the deeper, and memories all the more vivid, because they represent a series of juxtaposed, successive, partial impressions, which multiply each other, and mutually co-operate, so that they appeal to one another, associate in a thousand forms, and, thus implanted by their innu merable roots in the sensorinin, become like a series of conjugated foci for exciting in it a condition of ereth ism.