What is heroism?

And I won't forget an interview I once heard on Austrian's TV given by a Polish cardiologist who, during World War II, had organized Warsaw ghetto upheaval. "What a heroic deed," exclaimed the reporter. "Listen," calmly replied the doctor, "to take a gun and shoot is no great thing; but if the SS leads you to a gas chamber or to a mass grave to execute you on the spot, and you can't do anything about it, except for keeping your head high and going your way with dignity, you see, this is what I would call heroism." He should know.