Book excerpt: This witty and provocative study of sex and marriage manuals reveals the patterns of permissiveness and prohibition, and, tellingly, the mechanisms of suasion and enforcement - from sermons and hellfire to mutilation and electroshock - that have informed popular sex education over the past hundred and twenty years. From the roaring '20s to the 1960s sexual revolution and after, Teaching America about Sex reveals that, even as sexual behavior changed during periods of upheaval, the prescriptive literature on sex has remained traditional at its core, promoting primarily sex within marriage for the purpose of reproduction.