Investigating the six most pervasive categories of human difference -- religion, nation, class, gender, race, and civilization -- Cannadine asks how determinative each of them has really been over the course of history. Without denying their power to motivate populations dramatically at particular moments, he reveals that in the long term none has proven remotely as divisive as the occasional absolutist cries of "us versus them" would suggest, whether Christian versus Muslim during the Crusades (and now), landed gentry versus peasantry during the Bolshevik Revolution, or Jews versus "Aryan race" in Nazi Germany. For most of recorded time, these same "unbridgeable" differences were experienced as just one identity among others; whatever most chroniclers, mythmakers, and demagogues would have us believe, history needs to be reimagined to include human solidarity and the countless fruitful interactions across these lines, which are usually left out of the picture.