Many people have good ideas, but few live to see those ideas define an era and even win a war. George Kennan did, even though he eventually backed away from the ramifications of his idea. In 1946, as the United States was trying to decide how to deal with the post-World War II world, Kennan weighed in with the famous “Long Telegram” from Moscow. The Soviet Union is “impervious to the logic of reason,” Kennan warned his superiors at the State Department, but “it is highly sensitive to the logic of force.” Thus began the policy of containment -- a...