United with the correlated impressions that emanate from the minute structure of our muscles when in action, they make part and parcel of a number of complex notions, by which the understanding profits, and which are incessantly laid under contribution without our having any clear consciousness of the fact.
It is chiefly tactile impressions that form the special contingent destined to provoke the reactions of the intellectual sphere.
Radiated from the extremities of the peripheral plexuses, gifted with a special organization (sensitive papillae, tactile corpuscles of Pacini), these impressions furnish the intellect with a number of notions, not very numerous, it is true, but very precise, respecting the different qualities of bodies in contact with them. It is by means of them that we form our judgments respect ing the dimensions and surface-condition of external bodies, and respecting their motion, temperature, and de gree of dryness or moisture. It is by means of them and their fellows of muscular sensibility that we are informed of the expenditure of nerve-power necessary to gauge the weight of heavy bodies, to lift them, and indirectly acquire a precise notion of their volume and solidity.
This special contingent of sensitive elements, by means of which the notion of human personality is developed and maintained, and by means of which also we are constantly in contact with the things of the world—this contingent, I say, is still destined to vibrate in harmony with all the mental faculties, and to give specific bent to the character of the individual, as well as to the creations of his mind. We may say, then, that a greater or less degree of perfectionment, and a greater or less degree of sensitive power in the sensitive regions, find their counterpart in the central regions, and that the greater the degree of physical, the greater will be the degree of moral sensibility.
We all know how fine, delicate, and sensitive is the skin of women in general, and particularly of those who live in idleness and do no manual work— how their sensitive nervous plexuses are in a manner exposed naked to exciting agencies of all sorts, and how, from this very fact, this tactile sensibility, inces santly awake, and incessantly in vibration, keeps their mind continually informed of a thousand sensations that escape us men, and of tactile subtleties of which we have no notion. Thus in idle women of society, and
men with a fine skin, mental aptitudes are developed and maintained in the direct ratio of the perfection ment and delicacy of sensibility of the skin. The perfection of touch becomes in a manner a second sight, which enables the mind to feel and see fine details which escape the generality of men, and constitutes a quality of the first order, moral tact, that touch of the soul (toucher de Fame), as it has been called, which is the characteristic of organizations with a delicate and impressionable skin, whose sensorium, like a tense cord, is always ready to vibrate at the contact of the slightest impressions.
Inversely, compare the thick skin of the man of toil, accustomed to handle coarse tools and lift heavy bur dens, and in whom the sensitive plexuses are removed from the bodies they touch by a thick layer of epithelial callosities, and see if, after an examination of his intel lectual and moral sensibility, you are understood when you endeavour to evoke in him some sparks of those delicacies of sentiment that so clearly characterize the mental condition of individuals with a fine skin. On this point experience has long ago pronounced judg. meat, and we all know that we must speak to every one in the language he can comprehend, and that to en deavour to awaken in the mind of a man of coarse skin a notion of the delicacies of a refined sentiment is to speak to a deaf man of the deliciousness of harmony and to a blind man of the beauties of colours.* Evolution of Optic impressions.—The luminous vibra tions, directly transformed into nervous vibrations by the peculiar action of the retina, are all at first con centrated in the grey centres of the optic thalamus devoted to them, and radiated thence, chiefly into the antero-lateral regions of the cerebral cortex. They arrive in the sensorium, as we have already described, with different degrees of rapidity in different indi viduals,t and from the time when they come in the morning to illuminate the nervous plexuses of the sen sorium they are continuous, and by their incessant stimulation during the period of waking maintain the activity of the cerebral cells in continued erethism.