isolate the city. The amateur and _dilettante_ of the Renaissance
found a rare opportunity in warfare; and this passion for war and its
preparations occurs frequently among these early artists. Leonardo
designed scores of military engines. Francesco di Giorgio has left a
whole bookful of such sketches, in one of which he anticipates the
torpedo-boat.[84] So, too, Michael Angelo took his share in erecting
fortifications, though he did not fritter away so much time on
experiments as some of his contemporaries. Donatello and his
colleagues did not even leave us plans to compensate for their
ignominious failure. One is struck by the confidence of these
Renaissance people, not only in art but in every walk of life. They
were so sure of success, that failure came to be regarded as
surprising, and very unprofessional. Michael Angelo had no conception
of possible failure. He embarked upon the colossal statue of the Pope
when quite inexperienced in casting; he was the first to taunt
Leonardo on his failure to make the equestrian statue. When somebody
failed, the work was handed over to another man, who was expected to
succeed. Thus Ciuffagni had to abandon an unpromising statue, _quod
male et inepte ipsam laboravit_,[85] and the David of Michael Angelo
was made from a block of marble upon which Agostino di Duccio had
already made fruitless attempts.

[Footnote 80: The niche was completed about 1424-5. There is a drawing
of it in Vettorio Ghiberti's Note-book, p. 70. Landucci, in his
"Diario Fiorentino," says that Verrocchio's group was placed in it on
June 21, 1483.]

[Footnote 81: _Cf._ Payments to Andrea Moscatello, for painted and
glazed terra-cotta for the Paduan altar. May 1449.]