2. Organic form sub-dominant. Basso-relievo or intaglio. To be more abstract in proportion to the reduction of depth; to be also more rigid and simple in contour; to be touched with color more boldly and in an increased degree, exactly in proportion to the reduced depth and fulness of form, but still in a system non-concurrent with their forms. 3. Organic form abstracted to outline. Monochrome design, still farther reduced to simplicity of contour, and therefore admitting for the first time the color to be concurrent with its outlines; that is to say, as its name imports, the entire figure to be detached in one color from a ground of another. 4. Organic forms entirely lost. Geometrical patterns or variable cloudings in the most vivid color. On the opposite side of this scale, ascending from the color pattern, I would place the various forms of painting which may be associated with architecture: primarily, and as most fit for such purpose, the mosaic, highly abstract in treatment, and introducing brilliant color in masses; the Madonna of Torcello being, as I think, the noblest type of the manner, and the Baptistery of Parma the richest: next, the purely decorative fresco, like that of the Arena Chapel; finally, the fresco becoming principal, as in the Vatican and Sistine. But I cannot, with any safety, follow the principles of abstraction in this pictorial ornament; since the noblest examples of it appear to me to owe their architectural applicability to their archaic manner; and I think that the abstraction and admirable simplicity which render them fit media of the most splendid coloring, cannot be recovered by a voluntary condescension. The Byzantines themselves would not, I think, if they could have drawn the figure better, have used it for a color decoration; and that use, as peculiar to a condition of childhood, however noble and full of promise, cannot be included among those modes of adornment which are now legitimate or even possible. There is a difficulty in the management of the painted window for the same reason, which has not yet been met, and we must conquer that first, before we can venture to consider the wall as a painted window on a large scale. Pictorial subject, without such abstraction, becomes necessarily principal, or, at all events, ceases to be the architect's concern; its plan must be left to the painter after the completion of the building, as in the works of Veronese and Giorgione on the palaces of Venice.