Now let us pause for a moment, and observe the general effect of the lines, which we can do by turning to the skeleton drawing on transparent paper. It lays bare the plan of the composition, and we can see that it is a geometric composition of repetition and contrasts, of horizontal, vertical, diagonal and curved lines, balanced so as to unite into one single impression. To myself the impression is of looking into the interior of a circular building, with a vaulted roof. I remember just such a building in Rome; the Pantheon, built in honor of all the gods, but now, as in Raphael’s time, a temple of the Church. As you enter it an altar faces you across the stretch of pavement, and the lines of the architecture, as it circles round you and above you, are very similar to these lines, while overhead the ribs or radiating lines of the vaulted ceiling suddenly stop, for there is a circular opening at the top, through which you can see the sky, and the light strikes down through it in diagonal shafts of light.