Sigmund Freud,
Three Contributions to the Theory of Sex
“ Sexual Utilization of the Anal Opening.—It is even more obvious than in the former case that it is the loathing which stamps as a perversion the use of the anus as a sexual aim. But it should not be interpreted as espousing a cause when I observe that the basis of this loathing—namely, that this part of the body serves for the excretion and comes in contact with the loathsome excrement—is not more plausible than the basis which hysterical girls have for the disgust which they entertain for the male genital because it serves for urination. ”
