Two pictures painted in the year 1907 can conveniently be taken as the starting point of twentieth-century art. They are Matisse's Blue Nude and Picasso's Demoiselles d'Avignon; and both these cardinal, revolutionary pictures represent the nude. The reason is that the revolt of twentieth-century painters was not against academicism: that had been achieved by the impressionists. It was a revolt against the doctrine, with which the impressionists implicitly agreed, that the painter should be no more than a sensitive and well-informed camera. And the very elements of symbolism and abstraction that made the nude an unsuitable subject for the impressionists commended it to their successors. When art was once more concerned with concepts rather than sensations, the nude was the first concept that came to mind.