Excerpts from John Harvey Kellogg, 1852-1943.. Plain facts for old and young : embracing the natural history and hygiene of organic life. Electronic Text Center, University of Virginia Library
If illicit commerce of the sexes is a heinous sin, self-pollution, or masturbation, is a crime doubly abominable. As a sin against nature, it has no parallel except in sodomy (see Gen. 19:5; Judges 19:22). It is the most dangerous of all sexual abuses because the most extensively practiced. The vice consists in an excitement of the genital organs produced otherwise than in the natural way. It is known by the terms, self-pollution, self-abuse, masturbation, onanism, manustupration, voluntary pollution, and solitary or secret vice. The vice is the more extensive because there are almost no bounds to its indulgence. Its frequent repetition fastens it upon the victim with a fascination almost irresistible! It may be begun in earliest infancy, and may continue through life.
Even though no warning may have been given, the transgressor seems to know, instinctively, that he is committing a great wrong, for he carefully hides his practice from observation. In solitude he pollutes himself, and with his own hand blights all his prospects for both this world and the next. Even after being solemnly warned, he will often continue this worse than beastly practice, deliberately forfeiting his right to health and happiness for a moment’s mad sensuality.