After these things, in the year 1401, now that sculpture had risen to so great a height, it was determined to reconstruct the two bronze doors of the Church and Baptistery of S. Giovanni, since, from the death of Andrea Pisano to that day, they had not had any masters capable of executing them. This intention being, therefore, communicated to those sculptors who were then in Tuscany, they were sent for, and each man was given a provision and the space of a year to make one scene; and among those called upon were Filippo and Donato, each of them being required to make one scene by himself, in competition with Lorenzo Ghiberti, Jacopo[17] della Fonte, Simone da Colle, Francesco di Valdambrina, and Niccolò d'Arezzo. These scenes, being finished in the same year and being brought together for comparison, were all most beautiful and different one from the other; one was well designed and badly wrought, as was that of Donato; another was very well designed and diligently wrought, but the composition of the scene, with the gradual diminution of the figures, was not good, as was the case with that of Jacopo della Quercia; a third was poor in invention and in the figures, which was the manner wherein Francesco di Valdambrina had executed his; and the worst of all were those of Niccolò d'Arezzo and Simone da Colle. The best was that of Lorenzo di Cione Ghiberti, which had design, diligence, invention, art, and the figures very well wrought. Nor was that of Filippo much inferior, wherein he had represented Abraham sacrificing Isaac; and in that scene a slave who is drawing a thorn from his foot, while he is awaiting Abraham and the ass is browsing, deserves no little praise.
The scenes, then, being exhibited, Filippo and Donato were not satisfied with any save with that of Lorenzo, and they judged him to be better qualified for that work than themselves and the others who had made the other scenes. And so with good reasons they persuaded the Consuls to allot the work to Lorenzo, showing that thus both the public and the private interest would be best served; and this was indeed the true goodness of friendship, excellence without envy, and a sound judgment in the knowledge of their own selves, whereby they deserved more praise than if they had executed the work to perfection. Happy spirits! who, while they were assisting one another, took delight in praising the labours of others. How unhappy are those of our own day, who, not sated with injuring each other, burst with envy while rending others. The Consuls besought Filippo to undertake the work in company with Lorenzo, but he refused, being minded rather to be first in an art of his own than an equal or a second in that work. Wherefore he presented the scene that he had wrought in bronze to Cosimo de' Medici, who after a time had it placed on the dossal of the altar in the old Sacristy of S. Lorenzo, where it is to be found at present; and that of Donato was placed in the Guild of the Exchange.
The commission being given to Lorenzo Ghiberti, Filippo and Donato, who were together, resolved to depart from Florence in company and to live for some years in Rome, to the end that Filippo might study architecture and Donato sculpture; and this Filippo did from his desire to be superior both to Lorenzo and to Donato, in proportion as architecture is held to be more necessary for the practical needs of men than sculpture and painting. After he had sold a little farm that he had at Settignano, they departed from Florence and went to Rome, where, seeing the grandeur of the buildings and the perfection of the fabrics of the temples, Filippo would stand in a maze like a man out of his mind. And so, having made arrangements for measuring the cornices and taking the ground-plans of those buildings, he and Donato kept labouring continually, sparing neither time nor expense. There was no place, either in Rome or in the Campagna without, that they left unvisited, and nothing of the good that they did not measure, if only they could find it. And since Filippo was free from domestic cares, he gave himself over body and soul to his studies, and took no thought for eating or sleeping, being intent on one thing only—namely, architecture, which was now dead (I mean the good ancient Orders, and not the barbarous German, which was much in use in his time). And he had in his mind two vast conceptions, one being to restore to light the good manner of architecture, since he believed that if he could recover it he would leave behind no less a name for himself than Cimabue and Giotto had done; and the other was to find a method, if he could, of raising the Cupola of S. Maria del Fiore in Florence, the difficulties of which were such that after the death of Arnolfo Lapi there had been no one courageous enough to think of raising it without vast expenditure for a wooden framework. Yet he did not impart this his invention to Donato or to any living soul, nor did he rest in Rome till he had considered all the difficulties connected with the Ritonda, wondering how the vaulting was raised. He had noted and drawn all the ancient vaults, and was for ever studying them; and if peradventure they had found pieces of capitals, columns, cornices, and bases of buildings buried underground, they would set to work and have them dug out, in order to examine them thoroughly. Wherefore a rumour spread through Rome, as they passed through the streets, going about carelessly dressed, so that they were called the "treasure-seekers," people believing that they were persons who studied geomancy in order to discover treasure; and this was because they had one day found an ancient earthenware vase full of medals. Filippo ran short of money and contrived to make this good by setting jewels of price for certain goldsmiths who were his friends; and thus he was left alone in Rome, for Donato returned to Florence, while he, with greater industry and labour than before, was for ever investigating the ruins of those buildings. Nor did he rest until he had drawn every sort of building—round, square, and octagonal temples, basilicas, aqueducts, baths, arches, colossea, amphitheatres, and every temple built of bricks, from which he copied the methods of binding and of clamping with ties, and also of encircling vaults with them; and he noted the ways of making buildings secure by binding the stones together, by iron bars, and by dove-tailing; and, discovering a hole hollowed out under the middle of each great stone, he found that this was meant to hold the iron instrument, which is called by us the ulivella,[18] wherewith the stones are drawn up; and this he reintroduced and brought into use afterwards. He then distinguished the different Orders one from another—Doric, Ionic, and Corinthian; and so zealous was his study that his intellect became very well able to see Rome, in imagination, as she was when she was not in ruins. In the year 1407 the air of that city gave Filippo a slight indisposition, wherefore, being advised by his friends to try a change of air, he returned to Florence. There many buildings had suffered by reason of his absence; and for these, on his arrival, he gave many designs and much advice.
In the same year a congress of architects and engineers of the country was summoned by the Wardens of Works of S. Maria del Fiore and by the Consuls of the Guild of Wool, to discuss methods for raising the cupola. Among these appeared Filippo, giving it as his advice that it was necessary, not to raise the fabric directly from the roof according to the design of Arnolfo, but to make a frieze fifteen braccia in height, with a large round window in the middle of each of its sides, since not only would this take the weight off the supports of the tribunes, but it would become easier to raise the cupola; and models were made in this way, and were put into execution. Filippo, being restored to health after some months, was standing one morning in the Piazza di S. Maria del Fiore with Donato and other craftsmen, when they began to talk of antiquities in connection with sculpture, and Donato related how, when he