part of the organism, instead of accepting the stimulation, repels it. And it is not merely a difference of degree that separates perception from affection, but a difference in kind.
Now, we have considered the living body as a kind of centre whence is reflected on the surrounding objects the action which these objects exercise upon it: in that reflexion external perception consists. But this centre is not a mathematical point; it is a body, exposed, like all natural bodies, to the action of external causes which threaten to disintegrate it. We have just seen that it resists the influence of these causes. It does not merely reflect action received from without; it struggles, and thus absorbs some part of this action. Here is the source of affection. We might therefore say, metaphorically, that while perception measures the reflecting power of the body, affection measures its power to absorb.
But this is only a metaphor. We must consider the matter more carefully, in order to understandAffection differs from perception in that it is real instead of virtual action. clearly that the necessity of affection follows from the very existence of perception. Perception, understood as we understand it, measures our possible action upon things, and thereby, inversely, the possible action of things upon us. The greater the body's power of action (symbolized by a higher degree of complexity in the nervous system), the wider is the field that perception embraces. The distance which separates our body from an object
