DREAMS.
THE automatic activity of the cerebral cells reveals itself also, in a very distinct manner, at night in the form of persistent impressions—dreams. It naturally follows, from what we have already explained, that, in reality, dreams are nothing but the persistent vibra tion of certain groups of cells in a condition of erethism, when the greater number of their fellows are already plunged into the collapse of sleep.
This persistent vibration of the nervous elements may be explained physiologically, either by the fact of a strong super-excitation occurring in consequence of too prolonged exercise, or because of some special ex citability, some peculiar receptive condition of certain cell-territories, which have felt external stimulations more intensely than tile neighbouring regions. It is, then, sufficient that a certain number of them shall continue in vibration, in order that these shall become centres of appeal for other agglomerations of cells with which they have either more intimate affinities, or more or less facility of anastomosis. Hence arises a series of revivals of past impressions, of which we scarcely catch the sense, but which have secret connexions one with another (unconscious memory) ; a series of unex pected and disorderly ideas, which follow one another in the strangest forms. They are developed by the mere automatic forces of the cerebral cells abandoned to their own will, and freed from the directing in fluence of sensorial impressions (visual impressions), which, in the natural order of things, keep them awake and regulate their diurnal mode of activity.* Hence those unexpected apparitions which surprise us in dreams, and which are nothing but the result of the partial awakening of certain cells, which thus cause a series of long-forgotten impressions to rise again in the sen sorium. These, however, are in reality never anything but impressions which make a part of the stores we have acquired, which reveal themselves in our dreams, and which, probably under the influence of local condi tions of circulation, neighbouring impressions, &c., re
vive from out the depths of our past. To dream of anything, we must have seen it in one fashion or another. It is not rare, in seeking out the origin of certain dreams, to recognize that a great number have a more or less direct relation to an impression that was more or less strongly impressed upon us in the waking state, and that they are but a species of echo of this impression, associated with more or less heterogeneous impressions.t Hence, again, those curious phenomena through which dreams produce in us subsequent emotions which so pro foundly overwhelm us.
These emotions, as we have said, are necessarily asso ciated with the former impressions which have given them birth. They live with the same life, so that the appeal of the former inevitably evokes its fellow. If the first sight of any person, or spectacle, or scene, have caused us a moment of pleasure or anxiety, the reminiscence evoked by the same objects will be followed by the same emotions of our natural sensibility. In the domain of dreams the same phenomena unfold themselves in the same concatenation ; if one idea or agreeable memory arise in Lhe psychical sphere, in con sequence of a state of erethism in a special region of thy brain, immediately an analogous condition of con comitant satisfaction will be felt in the sensoriiim—if an idea of quite another nature should arise, either spon taneously or through some disturbance occurring in the visceral innervation (cardiac anxiety, gastric pain, irrita tion of the genital organs) ; if the mind, for instance, gives birth to conceptions regarding precipices, scenes of murder, etc. ; at the same time analogous states are developed in the emotional regions of our organism, and this artificial evocation of sensibility may pro duce a shock—a dynamic effect--intense and power ful enough to awaken the sleeping cerebral cells. Thus it is always the mere automatic forces of the nervous elements which regulate and govern the world of our and sentiments, sleeping as well a waking.