Being afterwards summoned, with the other painters, to execute the work that Pope Sixtus IV had undertaken in the Chapel of the Palace, he laboured there in company with Sandro Botticelli, Domenico Ghirlandajo, the Abbot of S. Clemente, Luca da Cortona, and Pietro Perugino, and painted three scenes with his own hand, wherein he depicted the Submersion of Pharaoh in the Red Sea, the Preaching of Christ to the people on the shore of the Sea of Tiberias, and the Last Supper of the Apostles with the Saviour. In this last scene he made an octagonal table drawn in perspective, with the ceiling above it likewise octagonal, the eight angles of which he foreshortened so well as to show that he had as good a knowledge of this art as any of the others. It is said that the Pope had offered a prize, which was to be given to the man who, in the judgment of the Pontiff himself, should turn out to have done the best work in these pictures. The scenes finished, therefore, His Holiness went to see them; and each of the painters had done his utmost to merit the said prize and honour. Cosimo, feeling himself weak in invention and draughtsmanship, had sought to conceal his shortcomings by covering his work with the finest ultramarine blues and other lively colours, and had illuminated his scenes with a plentiful amount of gold, so that there was no tree, or plant, or drapery, or cloud, that was not thus illuminated; for he was convinced that the Pope, like a man who knew little of that art, must therefore give him the prize of victory. When the day arrived on which the works of all were to be unveiled, that of Cosimo was seen with the rest, and was scorned and ridiculed with much laughter and jeering by all the other craftsmen, who all mocked him instead of having compassion on him. But the scorners turned out to be the scorned, for, as Cosimo had foreseen, those colours at the first glance so dazzled the eyes of the Pope, who had little knowledge of such things, although he took no little delight in them, that he judged the work of Cosimo to be much better than that of the others. And so, causing the prize to be given to him, he bade all the others cover their pictures with the best blues that could be found, and to pick them out with gold, to the end that they might be similar to those of Cosimo in colouring and in richness. Whereupon the poor painters, in despair at having to satisfy the small intelligence of the Holy Father, set themselves to spoil all the good work that they had done; and Cosimo laughed at the men who had just been laughing at his methods.