In a career spanning three decades and all continents, save perhaps Antarctica, Robert D. Kaplan has become our American Odysseus, forever ranging, it seems, across the oceans, penetrating far and legendary lands, collecting stories of warriors, priests, and princes that are passed on to eager listeners. Like the wily king of Ithaca, Kaplan, too, has finally come home, turning his critical eye toward his native land. After sixteen books limning nearly every global security issue of importance, Kaplan now asks his American readers to turn inward, to look carefully at their own country in order to understand why they do what they do abroad.

Those who have read Kaplan know that geography above all shapes his worldview. Unlike those who begin with ideology as the driving force in American history, such as Robert Kagan, in his Dangerous Nation (2006), or those who,...