280 THE FIFTEENTH CENTURY. Chap. X. use of girdles or belts, a method in which he was faith fully followed by Mantegna and Michael Angelo. He took into due account the action of the joints on the sur face of the flesh, and introduced the necessary folds on the skin of the inner bends, whilst he rendered the tension of the other parts or their repose by large and massive planes, according to the rules which Leonardo da Vinci afterwards laid down in one of his treatises. Yet even these qualities in him were not unalloyed, and the critic is forced to admit that he fell into occasional conventionalism, lost sight of the necessary simplicity, and overcharged his draperies with useless detail. The greater genius of Michael Angelo was not indeed free from this reproach; but if conventional, and unselect, he avoided the too fre quent error of his predecessor. The powerful and stern figures of SS. Peter and Mark at Orsanmichele, of the Zuccone or Baldpate and other Evangelists on the westside of the Campanile of S. M. del Fiore at Florence, are all examples of the qualities that were combined in Donatello. It is true that the statues of the Campanile are not so cleverly adapted as they might be to the spaces which they were intended to fill. But the master was not often at fault in this respect; and Vasari gives a telling account of the manner in which, being intrusted with the execution of the S. Mark of Orsanmichele, and having finished it according to his judgment in the form best suited to the position it was to occupy, he discontented the syndics of the Linaiuoli by showing them the statue on the ground, and, a few days after, roused their admiration to the highest pitch, by discovering it unaltered in its niche. 1 Whether Dona tello owed this scientific application of the law of optics to statuary to Brunelleschi, or to his own study of the antique, it was an eminent quality in him, and the art of creating form so as to appear natural when seen at 1 Vas. Vol. III. p. 249—50.