Civilization depends on the health of the traditional family. That sentiment has become a truism among social conservatives, who typically can't explain what they mean by it. Which is why it sounds like right-wing boilerplate to many contemporary ears. The late Harvard sociologist Carle C. Zimmerman believed it was true, but he also knew why. In 1947, he wrote a massive book to explain why latter-day Western civilization was now living through the same family crisis that presaged the fall of classical Greece and Rome. His classic "Family and Civilization," which has just been republished in an edited version by...