"Only Yesterday" by Frederick Lewis Allen is a history of the United States during the 1920s which not only lists names and numbers but describes the common tendencies in thought and attitude during the time and how they were changing. The chapter on "The Revolution in Manners and Morals" goes into details on the changing moral standards of the 1920s that most history books briefly allude to. It is useful to have an understanding of where conservative attitudes are coming from, even as they have evolved over the years.