The obvious defects and the salient qualities of all he afterwards performed as architect seem due to the forced diversion of his talent at this period to a type of art he had not properly assimilated.

Architecture was not the natural mistress of his spirit.

He bent his talents to her service at a Pontiff's word, and, with the honest devotion to work which characterised the man, he produced renowned monuments stamped by his peculiar style.
Nevertheless, in building, he remains a sublime amateur, aiming at scenical effect, subordinating construction to decoration, seeking ever back toward opportunities for sculpture or for fresco, and occasionally (as in the cupola of S.Peter's) hitting upon a thought beyond the reach of inferior minds.
The paradox implied in this diversion of our hero from the path he ought to have pursued may be explained in three ways.

First, he had already come to be regarded as a man of unique ability, from whom everything could be demanded.

Next, it was usual for the masters of the Renaissance, from Leo Battista Alberti down to Raffaello da Urbino and Lionardo da Vinci, to undertake all kinds of technical work intrusted to their care by patrons.