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 was returning from Rome, he had made the journey through Orvieto, in order to see that marble facade of the Duomo, a work greatly celebrated, wrought by the hands of diverse masters and held to be something notable in those times; and how, in passing afterwards by Cortona, he entered the Pieve and saw a very beautiful ancient sarcophagus, whereon there was a scene in marble--a rare thing then, when there had not been unearthed that abundance which has been found in our own day. And as Donato went on to describe the method that the master of that work had used in its execution, and the finish that was to be seen therein, together with the perfection and the excellence of the workmanship, Filippo became fired with an ardent desire to see it, and went off on foot just as he was, in his mantle, cap, and wooden shoes, without saying where he was going, and allowed himself to be carried to Cortona by the devotion and love that he bore to art. And having seen the sarcophagus, and being pleased with it, he made a drawing of it with the pen, and returned with that to Florence, without Donato or any other person knowing that he had been away, for they thought he must have been drawing or inventing something.