The qualities of wilfulness and amateurishness and seeking after picturesque effect, upon which I am now insisting, spoiled Michelangelo's work as architect, until he was forced by circumstance, and after long practical experience, to confront a problem of pure mathematical construction. In the cupola of S. Peter's he rose to the stern requirements of his task. There we find no evasion of the builder's duty by mere surface-decoration, no subordination of the edifice to plastic or pictorial uses. Such side-issues were excluded by the very nature of the theme. An immortal poem resulted, an aërial lyric of melodious curves and solemn harmonies, a thought combining grace and audacity translated into stone uplifted to the skies. After being cabined in the vestibule to the Laurentian Library, our soul escapes with gladness to those airy spaces of the dome, that great cloud on the verge of the Campagna, and feels thankful that we can take our leave of Michelangelo as architect elsewhere. VI While seeking to characterise what proved pernicious to contemporaries in Michelangelo's work as architect, I have been led to concentrate attention upon the Library at S. Lorenzo. This was logical; for, as we have seen, Vasari regarded that building as the supreme manifestation of his manner. Vasari never saw the cupola of S. Peter's in all its glory, and it may be doubted whether he was capable of learning much from it. The sacristy demands separate consideration. It was an earlier work, produced under more favourable conditions of place and space, and is in every way a purer specimen of the master's style. As Vasari observed, the Laurentian Library indicated a large advance upon the sacristy in the development of Michelangelo's new manner.