When Capra first pitched Stewart on the role of George Bailey for ““It’s a Wonderful Life,’’ the director was briefly seized by self-doubt: ““This is the lousiest piece of cheese I ever heard of,’’ he thought. Ticket sales in 1947 were so lackluster that Capra had to place his production company in bankruptcy. James Agee compared the movie to ““A Christmas Carol,’’ but many other critics savaged it. ““A figment of pure Pollyanna platitudes,’’ said The New York Times. The New Republic accused the film of trying ““to convince audiences that American life is exactly like the Saturday Evening Post covers of Norman Rockwell.''

A half century later, these movies lie deep in the marrow of America. For all his acting brilliance in Hitchcock films and Westerns, Jimmy Stewart’s most lasting contribution lies in two unforgettable roles. Sen. Jefferson Smith changed how we view our politics; George Bailey of Bedford Falls changed how we view ourselves.

““Mr. Smith’’ is now the premier allegory for idealism in Washington. That’s good for inspiring integrity and resistance to special interests. Unfortunately, sanctimonious showboats pretending to be Mr. Smith now use the once rare filibuster as a parliamentary gimmick to defend pork at home. And the film’s cartoonish qualities make it harder to see that complexity plays a larger role in politics than venality. Even so, Jeff Smith holds out the promise of using smarts (in the form of Jean Arthur) and shame to reclaim innocence. That’s a powerful idea in a cynical world. By emblazoning those terms of debate on the consciousness of the American public, Capra and Stewart at least give virtue in politics a fighting chance.

““It’s a Wonderful Life’’ is far darker than any Norman Rockwell picture and, with its dissection of the local power structure, far more socially conscious than most movies today. And it’s not truly sentimental, a word that suggests a cheap, easy way into the heart. Like Jeff Smith, George Bailey is a much angrier man than the casual viewer may remember. ““Will I ever get out of this crummy Bedford Falls?’’ he laments, as he sacrifices his ambitions for college and travel to fulfill responsibilities at home. He’s prone to self-pity, not to mention the selfishness of suicide. But with the help of Clarence the angel, George comes to the central insights necessary for living happily in this country: a good man is a great man, friendship is the real wealth, no one is born a failure.

Most art challenges middle-class values. That is one if its important functions. But art can also illuminate and make precious what we take for granted. Jimmy Stewart managed to inhabit abstract ideas like democracy and community and make them real for millions. This didn’t just tell us about ourselves; it made us try to be better, which is no small legacy for any man.