Touch, however, differs in some remarkable particulars from the other senses. There is no distinct organ appropriated to the tactual sensations alone; and the various parts of the body by which these may be communicated may also be the instruments of other classes of sensations, all of which have been confounded under the general name of “ touch ” or “ feeling.”
The object of touch proper has no special name, like sound, colour, or smell; but in itself it is familiar to every one who has experienced the state of consciousness which results from the contact of his own body with another, when not sufficiently violent to rise into a positive sense of pleasure or pain. In this state there is a twofold consciousness; that part of the bodily organism being known at the same time as affected and as extended.
The former constitutes the sensation, the latter the perception; and in proportion as the former rises to a higher consciousness of pleasure or pain, the latter grows feebler, though never becoming wholly extinct. This double state, which has no appropriate name, may perhaps be distinguished in its twofold character by the name of Tactual Impression. In addition to this may be mentioned other modes of feeling communicated, partly at least, through the same organs, such as those of heat and cold, which have sometimes been regarded as the proper objects of the sense of touch, and the various lands of pain and pleasure produced by external applications.
It will be sufficient for our present purpose to notice that all of them belong to the class commonly known as secondary qualities of body; that is to say, affections of the different parts of the nervous organism, which, as apprehended, have no resemblance to any property of inorganic matter, though generally caused by some unknown power by which that matter is capable of affecting our organs.
***Excerpt from Henry Longueville Mansel, B.d.. Metaphysics or the philosophy of consciousness