Just as the development of life requires variation as well as heredity, and the development of a society needs experimental innovation as well as stabilizing custom, so the development of art in Western Europe involved not only the continuity of a tradition in skills and forms, and the stimulation of Byzantine and Moslem examples, but also the repeated turning of the artist from the school to nature, from ideas to things, from the past to the present, from the imitation of models to the expression of self.
