the differences of their vibrations, and declare in words what each is.
Fourthly, The vibrations excited in the sense of feeling by motion, distance, and figure, are so faint, and so various, that neither these words, nor any related expressions, can be supposed to excite any miniature vibrations in this sense. Yet still upon feeling motions and figures, and passing over distances, the differences of vibrations from pressure and muscular contraction, i.e. from the vis inertiæ of our own bodies, or of foreign matter, suggest to us the words expressing these, with their varieties, by association.
Fifthly, The great extent of the sense of feeling tends to make the miniatures fainter, especially as far as the external parts are concerned; and would probably have so powerful an effect upon the miniatures raised in the internal parts, as to make them by opposing destroy one another, did not all the impressions of the same nature, viz. all those from heat, from cold, from friction, &c. by whatever external part they enter, produce nearly the same effect upon the brain. Whence the several miniatures left by particular impressions of the same kind must strengthen one another in the internal parts, at the same time that they obliterate one another in the external ones. However, where a person has suffered much by a particular wound, ulcer, &c. it seems, according to the theory, that an idea of it should be left in the part affected, or corresponding region of the brain, or spinal marrow.
Sixthly, The visible ideas of the bodies which impress the several sensations of feeling upon us, are, like all other visible ones, so vivid and definite, that they mix themselves with, and somewhat obscure, the most vivid ideas of feeling, and quite overpower the faint ones. Sight communicates to us at once the size, shape, and colour of objects; feeling cannot do the last at all, and the two first only in a tedious way; and is scarce ever employed for that purpose by those who see. Hence persons born blind must have far more vivid and definite ideas of feeling than others. An inquiry into their real experiences would greatly contribute to correct, illustrate, and improve, the theory of ideas, and their associations.
The principal of these is the action of crying, which is in all animals, but especially young ones, the natural and necessary consequence of pain. I have already given some account of this action; but will here enter into a more particular detail of the circumstances, and their agreement with the foregoing theory.
Let us suppose then a young child to have a very painful impression made upon the skin, as by a burn. It is plain that the violent vibrations excited in the injured part will pass up to the
