We all think we know Stalin. He was the brutal and vengeful dictator of the Soviet Union from the late 1920s until 1953, when, mercifully, he died before he could do any more damage. He was the instigator of forced industrialization and collectivization, taking his country down a dead-end path to modernity from which its heirs are still trying to recover. As the valued ally of Great Britain and the United States during World War II, he was responsible for his country's great victory over Nazism, which cost, sometimes senselessly, the lives of 27 million Soviet citizens. He was the primary author of the Cold War, instigating such crises as the Berlin Blockade and the Korean conflict. And he killed millions.

Yet given Stalin's enormous importance to the history of the 20th century, it is remarkable how little we understand about his personality and motives. Norman Naimark reviews Paradoxes of Power, the first installment of a projected three-volume biography of Stalin by Princeton historian Stephen Kotkin.