Pleasure and Pain
There are two meanings of the word "pleasure, " and only one of the word "pain" -- words that are used by everyone in daily discourse without observing the difference in these meanings.
Pain is a sensation. In our bodies, there are peripheral and visceral nerve endings that, when stimulated, cause us to feel pain. Pleasure, in sharp distinction from pain, is not a sensation, though we feel it. We have no neurophysiological centers of pleasure.
The two meanings of pleasure refer to pleasures that we all feel. One is sensual pleasure, the pleasure that is an object of desire. Its bodily aspect is to be found in certain sensory stimulations, such as the pleasure we feel when we are thirsty on a hot day and are given a drink of cold liquid, the pleasure we feel when being tickled, the pleasure we feel when the tension of sexual desire is relieved by an orgasm.
These are all sensible and sensual pleasures that are objects of desire, even thought there are no neurophysiological spots on or in our bodies that are nerve endings for pleasure as there are such stimulatory nerve endings for pain. The erogenous zones maybe such physiological pleasure spots.
The other meaning of the word "pleasure" lies in the pleasure we feel when our desires are satisfied. It is the pleasure of contentment. We use the word "pleasure" in this way when we say that something we have done or something done to us pleases us.
This identification of pleasure with the satisfaction of desire give another meaning to the word "pain" that has no basis in our nervous system. We often say we are pained when we mean that we are discontented or dissatisfied.
Adler's Philosophical Dictionary (1995)
Great Ideas from the Great Books (1963)
by Mortimer J. Adler