I got to talk to Jane Jacobs once, toward the end of her life, an interview that is mentioned, in its properly Lilliputian proportion, in Robert Kanigel's new biography, "Eyes on the Street: The Life of Jane Jacobs" (Knopf). She was one of three people I have met in a lifetime of meeting people who had an aura of sainthood about them, the others being Iona Opie, the British folklorist who collected children's rhymes, and I. F. Stone, the independent American journalist. What they had in common was a sort of radiant self-reliance. They could say an obvious thing--that children are citizens of another country, that all governments lie--with the conviction that comes from having really found it out. They spoke for many, because they thought for themselves. Iona Opie made hanging around schoolyards to find small variants in jumping-rope rhymes seem essential to understanding humanity, and Izzy Stone made you feel unpatriotic for not printing your own biweekly page of political commentary. The ability to radiate certainty without condescension, to be both very sure and very simple, is a potent one, and witnessing it in life explains a lot in history that might otherwise be inexplicable--for instance, how a sixteen-year-old girl could lead the French Army to victory. Jane Jacobs's aura was so powerful that it made her, precisely, the St. Joan of the small scale. Her name still summons an entire city vision--the much watched corner, the mixed-use neighborhood--and her holy tale is all the stronger for including a nemesis of equal stature: Robert Moses, the Sauron of the street corner. The New York planning dictator wanted to drive an expressway through lower Manhattan, and was defeated, the legend runs, by this ordinary mom.