It is now necessary to ask what must be the interpretation of the use of these types of composition. Must we consider the pyramid the expression of passivity, the diagonal or V-shape, of activity? But the greatly predominating use of the second for landscapes would remain unexplained, for at least nothing can be more reposeful than the latter. It may aid the solution of the problem to remember that the composition taken as a whole has to meet the demand for unity, at the same time that it allows free play to the natural expression of the subject. The altar-piece has to bring about a concentration of attention to express or induce a feeling of reverence. This is evidently accomplished by the suggestion of the converging lines to the fixation of the high point in the picture,--the small area occupied by the Madonna and Child,--and by the subordination of the free play of other elements. The contrast between the broad base and the apex gives a feeling of solidity, of repose; and it seems not unreasonable to suppose that the tendency to rest the eyes above the centre of the picture directly induces the associated mood of reverence or worship. Thus the pyramidal form serves two ends; primarily that of giving unity, and secondarily, by the peculiarity of its shape, that of inducing the feeling-tone appropriate to the subject of the picture. Applying this principle to the so-called "active" pictures, we see that the natural movement of attention between the different "actors" in the picture must be allowed for, while yet unity is secured. And it is clear that the diagonal type is just fitted for this. The attention sweeps down from the high side to the low, from which it returns through some backward suggestion of lines or interest in the objects of the high side. Action and reaction--movement and return of attention--is inevitable under the conditions of this type; and this it is which allows the free play,--which, indeed, CONSTITUTES and expresses the activity belonging to the subject, just as the fixation of the pyramid constitutes the quietude of the religious picture. Thus it is that the diagonal composition is particularly suited to portray scenes of grandeur, and to induce a feeling of awe in the spectator, because only here can the eye rove in one large sweep from side to side of the picture, recalled by the mass and interest of the side from which it moves. The swing of the pendulum is here widest, so to speak, and all the feeling-tones which belong to wide, free movement are called into play. If, at the same time, the element of the deep vista is introduced, we have the extreme of concentration combined with the extreme of movement; and the result is a picture in the "grand style" --comparable to high tragedy--in which all the feeling-tones which wait on motor impulses are, as it were, while yet in the same reciprocal relation, tuned to the highest pitch. Such a picture is the "Finding of the Ring," Paris Bordone, in the