This book embodies the considered opinions of twenty-five years' practical experience of adult life--as an official reporter and journalist, as a voluntary war-worker, and as a married woman. For many of the thoughts and expressions used I am indebted to large numbers of men and women whom I cannot name, and with whom I have been personally and professionally associated in different parts of the world. I am also indebted to the following medical journals for the publication, during the last five years, of many letters, articles, notes, etc.: _The Lancet_, _The British Medical Journal_, _Public Health_, _Municipal Engineering_, _Hospital_, _New York Medical Journal_, etc., etc. I have to thank the Society for the Prevention of Venereal Disease, the National Birth-Rate Commission, and the Joint Select Committee (House of Lords) on Criminal Law Amendment Bills for recording various statements and evidence. It remains only to state this fact: That on January 25th, 1922, Sir Arbuthnot Lane, Sir Frederick Mott, Surgeon-Commander Hamilton Boyden, of the Royal Navy, and Mr. Harman Freese, of Freese & Moon, manufacturing chemists, of 59, Bermondsey Street, London, S.E.1, met at my home to decide upon the best medical formulae for self-disinfecting ointment for men and contraceptive-disinfecting-suppositories for women. Mr. Freese made up sanitary tubes and sanitary suppositories in accordance with these formulae, but he is prohibited by law from recommending these for the prevention of venereal disease, and forbidden to supply printed directions with them, whereas similar medicaments are being retailed with printed directions in the State of Pennsylvania, and the Health Department circularises medical practitioners thus:-- "The self-treatment packet, obtainable at drug stores, to arrest venereal infection after exposure, is approved by the State Department of Health on the same principle as is antitoxin given to diphtheria contacts. Proof is lacking that the use of this packet lowers social standards. Reduction in the incidence of venereal disease is a direct result." But not only in the clear, cool air of American State Departments of Health is the knowledge and love of sexual cleanliness fructifying. In the _Dublin Review_ for January-March, 1922, there is a wonderfully fine article on "The Church and Prostitution," by the Right Rev. Monsignor Provost W.F. Brown, D.D., V.G., in which he quotes from a very recent Moral Theology, "De Castitate," by the Rev. A. Vermeersch, S.J., Professor of Moral Theology at the Gregorian University, Rome, published in May, 1921. The author of "De Castitate" gives brief answers to three questions put to him, which Mgr. Brown quotes in the original Latin, and of which the following is a translation furnished by a Catholic priest:-- "You ask 1. Whether or not it is formally sinful to use antiseptic ointment before illicit intercourse.