Unluckily, during all the years which intervened between the Sistine vault and the Last Judgment, Michelangelo was employed upon architectural problems and engineering projects, which occupied his genius in regions far removed from that of figurative art. It may, therefore, be asserted, that although he did not retrograde from want of practice, he had no opportunity of advancing further by the concentration of his genius on design. This accounts, I think, for the change in his manner which we notice when he began to paint in Rome under Pope Paul III. The fourth stage in his development of form is reached now. He has lost nothing of his vigour, nothing of his science. But he has drifted away from Nature. All the innumerable figures of the Last Judgment, in all their varied attitudes, with divers moods of dramatic expression, are diagrams wrought out imaginatively from the stored-up resources of a lifetime. It may be argued that it was impossible to pose models, in other words, to appeal to living men and women, for the foreshortenings of falling or soaring shapes in that huge drift of human beings. This is true; and the strongest testimony to the colossal powers of observation possessed by Michelangelo is that none of all those attitudes are wrong. We may verify them, if we take particular pains to do so, by training the sense of seeing to play the part of a detective camera. Michelangelo was gifted with a unique faculty for seizing momentary movements, fixing them upon his memory, and transferring them to fresco by means of his supreme acquaintance with the bony structure and the muscular capacities of the human frame. Regarded from this point of view, the Last Judgment was an unparalleled success. As such the contemporaries of Buonarroti hailed it. Still, the breath of life has exaled from all those bodies, and the tyranny of the schematic ideal of form is felt in each of them. Without meaning to be irreverent, we might fancy that two elastic lay-figures, one male, the other female, both singularly similar in shape, supplied the materials for the total composition. Of the dramatic intentions and suggestions underlying these plastic and elastic shapes I am not now speaking. It is my present business to establish the phases through which my master's sense of form passed from its cradle to its grave. In the frescoes of the Cappella Paolina, so ruined at this day that we can hardly value them, the mechanic manner of the fourth stage seems to reach its climax. Ghosts of their former selves, they still reveal the poverty of creative and spontaneous inspiration which presided over their nativity.