strongest testimony to his architectural skill is derived from the
fact that he was commissioned in 1416 to make a model for the then
unfinished cupola of the Cathedral at Florence. Brunellesco and Nanni
di Banco also received similar orders. Brunellesco alone understood
the immense difficulty of the task, and in the next year he announced
his return to Rome for further research. In 1418 the sum of two
hundred gold florins was offered for the best model, and in 1419
Ghiberti, Nanni di Banco, Donatello and Brunellesco all received
payments for models. Donatello's was made of brick. Ultimately the
work was entrusted to Brunellesco, who overcame the ignorance and
intrigues which he encountered from all sides, his two staunch friends
being Donatello and Luca della Robbia. As to the nature of Donatello's
models we know nothing; it is, however, clear that his opinion was at
one time considered among the best available on a problem which
required knowledge of engineering. As a military engineer Donatello
was a failure. He was sent in 1429 with other artists to construct a
huge dam outside the besieged town of Lucca, in order to flood or
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