The definition of the American crime/gangster film is not stable. It is continuously modified according to the changes in the motion picture industry that reacts to the changes in American society. However, some things, certain uniquely American themes can always be tracked down in these movies. Probably the most important of these themes is the evaluation and reevaluation of the American Dream and the love of freedom. These ideas are ever-present, although they are reshaped and given new meanings from time to time. The dichotomy of alteration and permanence provide the genre with continuity and make it popular in all periods of cinematic history in America. This is the basis for new subgenres to be born, for example, the historical crime movie (Gangs of New York, Public Enemies) and the recycling and updating of classic forms to meet modern demands (Public Enemies).