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CH. XI.] upon the Elements. The organ which perceives those distinctions is that of Touch; and the part in which resides, primarily, the so-called sense of Touch is, in potentiality, what tangible impressions are in reality; for all sensation is a kind of impression. So that whatever, by its agency, makes something else to be as itself, can do so only from that something being already, as itself, in potentiality. Hence, we are not sensible of hot and cold, hard and soft, when manifested in the same degree as in ourselves, but perceive them only when in excess, as if the sensibility were some kind of mean between the contraries of sentient impressions, and able, as such, to judge of sentient perceptions. The mean, in fact, is critical—for it is either of the extremes in its relation to the other; and as that which is to perceive white and black may be neither one nor the other actually, and yet both potentially, so it is with the other senses, and with touch, which may be neither hot nor cold.

As vision was said to be, in some sense, perceptive of the visible and the invisible, and the other senses equally of their opposites, so Touch may be said to be perceptive of the tangible and the intangible; and by intangible is meant as well what differs but slightly from what is tangible, as air for instance, as what is in such excess as to be destructive of all sensation.

We have thus then spoken, although but superficially, upon each of the senses.