To confine ourselves, however, as closely as we may to painting, and leaving aside for the present the question of colour, which, as I have already said, is, in Florentine art, of entirely subordinate importance, there were three directions in which painting as Pollaiuolo and Verrocchio found it had greatly to advance before it could attain its maximum of effectiveness: landscape, movement, and the nude. Giotto had attempted none of these. The nude, of course, he scarcely touched; movement he suggested admirably, but never rendered; and in landscape he was satisfied with indications hardly more than symbolical, although quite adequate to his purpose, which was to confine himself to the human figure. In all directions Masaccio made immense progress, guided by his never failing sense for material significance, which, as it led him to render the tactile values of each figure separately, compelled him also to render the tactile values of groups as wholes, and of their landscape surroundings—by preference, hills so shaped as readily to stimulate the tactile imagination. For what he accomplished in the nude and in movement, we have his “Expulsion” and his “Man Trembling with Cold” to witness. But in his works neither landscape nor movement, nor the nude, are as yet distinct sources of artistic pleasure—that is to say, in themselves life-enhancing. Although we can well leave the nude until we come to Michelangelo, who was the first to completely realise its distinctly artistic possibilities, we cannot so well dispense with an enquiry into the sources of our æsthetic pleasure in the representation of movement and of landscape, as it was in these two directions—in movement by Pollaiuolo especially, and in landscape by Baldovinetti, Pollaiuolo, and Verrocchio—that the great advances of this generation of Florentine painters were made.