It has become a cliche to say that one person can make a difference, but the life of Mahatma Gandhi confronts us with the enduring truth of that statement. It is impossible to say exactly what moved people to revere and follow him and be imprisoned and beaten on his behalf in the thousands. No doubt, his ever gentle demeanor had a hand in that. His perpetual grace and joy, even in the face of terrible hardship, surely won some hearts and minds. His genuine ability to treat all men - Hindu, Muslim, Parsee, Sikh, Harijan, Christian, and Zulu - as brothers must have won even more.

Has there ever been someone who accomplished so much and at the same time thought less of herself? Before she had even turned forty, Florence Nightingale was the darling of the British public, the heroine of the Crimea. She could have sailed home to England and comfortably dined out on her fame for the remainder of her long days. Instead, she conducted a ruthless post-mortem on every moment of her wartime service and found herself entirely wanting. She did not try to hide her mistakes; instead, she sought to broadcast them so that everyone would understand what happens in unsanitary medical...