19. Thus what we know as pleasure and pain may be identified: pain is our perception of a body despoiled, deprived of the image of the soul; pleasure our perception of the living frame in which the image of the soul is brought back to harmonious bodily operation. The painful experience takes place in that living frame; but the perception of it belongs to the sensitive phase of the soul, which, as neighbouring the living body, feels the change and makes it known to the principle, the imaging faculty, into which the sensations finally merge; then the body feels the pain, or at least the body is affected: thus in an amputation, when the flesh is cut the cutting is an event within the material mass; but the pain felt in that mass is there felt because it is not a mass pure and simple, but a mass under certain (non-material) conditions; it is to that modified substance that the sting of the pain is present, and the soul feels it by an adoption due to what we think of as proximity.
And, itself unaffected, it feels the corporeal conditions at every point of its being, and is thereby enabled to assign every condition to the exact spot at which the wound or pain occurs. Being present as a whole at every point of the body, if it were itself affected the pain would take it at every point, and it would suffer as one entire being, so that it could not know, or make known, the spot affected; it could say only that at the place of its presence there existed pain – and the place of its presence is the entire human being. As things are, when the finger pains the man is in pain because one of his members is in pain; we class him as suffering, from his finger being painful, just as we class him as fair from his eyes being blue.
But the pain itself is in the part affected unless we include in the notion of pain the sensation following upon it, in which case we are saying only that distress implies the perception of distress. But (this does not mean that the soul is affected) we cannot describe the perception itself as distress; it is the knowledge of the distress and, being knowledge, is not itself affected, or it could not know and convey a true message: a messenger, affected, overwhelmed by the event, would either not convey the message or not convey it faithfully.