In 1888, Leo Tolstoy mysteriously declared that sexual intercourse should no longer exist. Years later he would admit to being "horrified" by this pronouncement, but still remained an ardent believer in sexual abstinence. Frequenter of brothels in his youth, father of thirteen children by his wife and at least two children by peasant women before he was married, Tolstoy now had the audacity to suggest that people should stop having sex. How can...