The sense of feeling is spread over the whole body, but employs itself differently in different parts. The sensation which results from feeling is excited by the contact of some foreign body to that of our own. If we apply a foreign body against the breast or shoulder we shall feel it, but without having a single idea of its form, because the breast or shoulder touches but one side only. It is the same with respect to all other parts which cannot bend themselves round or embrace at one time many parts of foreign bodies. Those parts of our body, which, like the hand, are divided into many flexible and moveable parts, and can apply themselves at one time upon different sides of a foreign body, are those only which can give us the ideas of their form and size.
It is not, therefore, because there are a greater quantity of nervous tufts at the extremity of the fingers than in any other part of the body, that the hand is, in effect, the principal organ of feeling, but merely because it is divided into many parts all moveable, all flexible, all acting at the same time, and are all obedient to the will; and which alone gives us distinct ideas of the figure and form of bodies. Feeling is no more than a contact of superficies, and the superficies of the hand are greater, in proportion, than that of any other part of the human body, because there is not any one which is so greatly divided. This advantage, when added to those derived from the flexibility of the fingers, suffices to render this part the most perfect organ to give us the exact and precise ideas of the form of bodies, and, if the hand had twenty fingers, it is not to be doubted but that the sense of feeling would be infinitely more perfect; and if we should suppose that it were divided into an infinity of parts we should have, even in the very moment of the touch, exact and precise ideas of the figure and difference of bodies, however small. If, on the contrary, the hand were without fingers, we should have but very imperfect and confused knowledge of the objects which surround us.
Animals which have hands appear to be the most acute; apes do things so resembling the mechanical actions of man that they seem to be actuated by the same sensations; but those animals which are deprived of hands having not any part divided and flexible enough to be able to twist round the superficies of bodies, they cannot have any precise notion either of the form or size of them. It is for this reason that we often see them frightened at objects which they ought to be the best acquainted with. The principal organ of their feeling is the muzzle, because it is divided in two parts by the mouth, and because the tongue serves them for touching bodies, and turning them, which they do over and over again, before they take them between their teeth. It may also be conjectured, that animals, which, as the scuttle-fish, the polypus, and many insects, have a great number of arms or paws, which they can unite and join, may also have an advantage over others, in knowing how to chuse what is most agreeable to them. Fishes, therefore, whose bodies are covered with scales, ought to be the most stupid of all animals, for they cannot have any knowledge of the form of bodies; and their sense of feeling must be very obtuse, since they cannot feel but through the scales. Thus all animals, whose bodies have no divided extremities, as arms, legs, paws, &c. will have much less sense of feeling than others. Serpents, however, are less stupid than fishes, because, although they have no extremities, and are covered with a hard and scaly coat, they have the faculty of bending round foreign bodies, and by that means obtaining some conception of their form and magnitude.
The two great obstacles to the exercise of the sense of feeling then are, first, the uniformity of the figure of the body of the animal, or the defect of the different divided and flexible parts; and secondly, the cloathing of the skin, whether with hair, feathers, scales, shells, &c. The more this cloathing is hard and solid, the less the sentiment of feeling will be; and the finer and more delicate the skin, the sense of feeling will be the more quick and exquisite. Women, among other advantages over men, have their skin more fine, and the sense of feeling more delicate.
The fœtus in the womb of the mother, has a very delicate skin; it must therefore feel every exterior impression in the most acute manner; but as it swims in a liquid, and as liquids break the action of all the causes which may occasion any shock, it can but very seldom be injured, and never without some violent shock be received by the mother. Although the sense of feeling depends, in a great measure upon the fineness of the skin, yet, as it can have but little exercise in the fœtus state, so can it have but little sensation arising from feeling.
In a new-born infant, the hands remain as useless as in the fœtus, because, by swaddling they are not permitted to make use of them, till the end of six or seven weeks; by this absurd custom, we retard the unfolding of this important sense on which all our knowledge depends; and therefore we should act more wisely, were we to allow the infant the free use of its hands the moment of its birth, as it would then sooner acquire ideas of the form of things; and who knows how far our first ideas have an influence over our subsequent ones? One man, perhaps, possesses more ingenuity, or capacity than another, merely because in his earliest infancy he was allowed to make a greater and readier use of this sense. As soon as children are indulged with the liberty of their hands, they endeavour to touch whatever is presented to them. They take pleasure in handling every thing they are capable of grasping; they seem as if desirous to find out the form of bodies, by feeling them on every side; and they amuse or instruct themselves in this manner with new objects. And which predilection for novelty remains our favourite amusement through life.
It is by feeling alone that we can attain any complete and certain intelligence, and it is by that alone, all the other senses are prevented from being perpetual sources of illusion and error. But in what manner is this important sense developed? In what manner are our first ideas attained? Have we not forgot every thing that passed during the cloud of infancy? How shall we trace our thoughts back to their origin? Even in attempting thus to trace them, is there not presumption? There is, and were the object in view of less importance, with justice might it be stigmatized, but as the mind cannot be employed in a more noble research, every effort may surely be exerted in so important a contemplation.
Let us suppose, then, a man newly brought into existence, whose body and organs were perfectly formed, but who, awaking amidst the productions of Nature, is an utter stranger to himself and every thing he perceives. Of a man thus circumstanced what would be the first emotions, the first sensations, the first opinions? Were he himself to give us a detail of his conceptions at this period, how would he express them? Might it not be in some measure as follows? And here let us suppose such a man to speak for himself.
“Well do I recollect that joyful, anxious moment, when I first became conscious of my own existence; I knew not what I was, where I was, nor from whence I came. On opening my eyes, what an addition to my surprise! The light of day, the azure vault of heaven, the verdure of the earth, the transparency of the waters, all employed, all animated my spirits, and filled me with inexpressible delight.
“At first, I imagined that all those objects were within me, and formed a part of myself. Impressed with this idea, I turned my eyes toward the sun, whose splendour instantly dazzled and overpowered me. Involuntarily I closed my eye-lids, though not without a slight sensation of pain; and, during this short interval of darkness, I imagined that I was about to sink into nothing.