But the rhythm of this picture, in what does it consist? Yes, in the movement, not of form, but of light. Uniting all the colors into a single harmony, it flows in and out through the lighter and darker parts of the composition; sometimes in a broad sweeping flood, as on the wall; sometimes in little pulses of movement, as it leaps from point to point; now losing itself in the hollow of a shadow, then reappearing in the gleam of a fold; all the while streaming through the picture in a continuous ebb and flow. In fact, as we study it, we gradually find that the light does for the parts of this composition what the lines of direction did in Raphael’s--it unites them in a rhythmic movement.