I guess I should have known I would one day write biography when, at the age of 10 or so, I discovered that the heroes I most craved to meet were not taxpaying residents of Nairobi, Kenya.

Alexander the Great, Tom Sawyer, Winston Churchill, and test pilot Chuck Yeager lived in "a world else- where," and seemed unlikely to visit mine, except perhaps on safari. Lacking their company, I was forced to improvise novels in which tow- headed aviators fought confusedly with Prime Ministers we...