IMPRESSIONS.
Evolution of Sensitive Impressions.—Sensitive impres sions in general comprehend not merely impressions of touch, contact, and pressure of bodies, but also those which give us the idea of temperature, and that of the activity of our muscles. They are designed, either isolatedly or simultaneously, to play a principal part in the phenomena of cerebral activity proper ; forming, as has been explained, an enormous contingent of connate excitations which are distributed in the domain of psychical activity proper as well as that of intellectual activity.* Radiating from the central regions of the optic thalami which represent the very centre of the brain, they do not as yet appear to have a very clearly defined localiza tion, as regards their ultimate distribution. Indeed, the fibres that radiate from the median centre appear as though they must distribute them equally throughout the different zones of the cerebral cortex.
The contingent of sensitive elements specially reserved for distribution in the field of psychical activity, as we have defined it, is represented by all those agglomera tions of sensitive excitations which, drawn from all the sensitive points of the organism, are conducted towards the central regions by the centripetal channels.
These agglomerated sensitive elements, incessantly vibrating with one accord, incessantly active, become in the sensorium the elements constituting our inner personality, our sentient unity. This is the special part played by sentient impressions as regards psychical activity proper ; and we see what an important part it is, they being the keystones of the whole edifice of our mental activity, since they produce by their synthesis the notion of a living individuality in exercise.
Genesis of the Notion of Happiness and Unhappiness.— Sensitive impressions are again reverberated in the sensorium in a very peculiar manner, exciting in it conditions which depend on them alone.
Thus from that pre-established consensus between the peripheral and central regions of the nervous system, on which we have so strongly insisted, this very remark able consequence results : that the special condition of the sensitive nerves (when affected by impressions which gratify their natural sensibility) is reflected upon the sensorium, and there develops a species of concord, by means of which it enters into unison with them.
When a warm atmosphere refreshes our skin with gentle perspiration, when comfortable repose revives our strength and restores to our fatigued muscles and aching joints their pristine flexibility and elasticity, we say that we are in a special condition of comfort— that this has given us pleasure.
This word pleasure characterizes a special state of our sensorium, a peculiar pitch of the sensibility, which is desired by every one, and which thus becomes a specific mode of existence of the sensoriunz, which fixes and perpetuates itself in us as a memory and a hope. It is a kind of specific sentiment, a species of standard sentiment with which we compare the greater number of the impressions that come to be reflected in us ; so that, by extension, the notion of the pleasure of our gratified sensitive nerves insensibly becomes subjective, to be transformed into the notion of happiness. It results from this mental evolution that when any act whatever of the human activity is judged of by us, we say that it is good, because it has produced in the sphere of our moral sensibility an impression equivalent to that produced in the domain of physical sensibility by a sensorial impression which has given us pleasure. And, inversely, whatever wounds or offends our physical sensibility—whatever gives us pain—places our senso rium in very different conditions from the foregoing, and thus becomes the subjective notion of unhappiness, to which we refer all the miseries of our moral sensibility.
In the domain of intellectual activity proper, sensitive impressions also come to be of the utmost importance.