It is related, says Vasari, of this master, that being commissioned to paint a picture of St. Thomas seeking the wound in the side of Christ, above the door of the church dedicated to that saint, in the Mercato Vecchio, he declared that he would make known in that work, the extent of what he had acquired and was capable of producing. He accordingly bestowed upon it the utmost care and consideration, and erected an enclosure around the place that he might not be disturbed until it should be completed. One day, his friend Donatello met him, and asked him, "What kind of work is this of thine, that thou art shutting up so closely?" Paolo replied, "Thou shalt see it some day; let that suffice thee." Donatello would not press him, thinking that when the time came, he should, as usual, behold a miracle of art. It happened one morning, as he was in the Mercato Vecchio, buying fruit, he saw Paolo uncovering his picture, and saluting him courteously, the latter anxiously demanded what he thought of his work. Donatello having examined the painting very closely, turned to the painter with a disappointed look, and said, "Why, Paolo, thou art uncovering thy picture at the very moment when thou shouldst be shutting it up from the sight of all!" These words so grievously afflicted the painter, who at once perceived that he would be more likely to incur derision from his boasted master-piece, than the honor he had hoped for, that he hastened home and shut himself up, devoting himself to the study of perspective, which, says Vasari, kept him in poverty and depression till the day of his death. If this story be true, Uccello must have painted the picture referred to in his old age.
The fame and success of Cimabue and Giotto, brought forth painters in abundance, and created schools all over Italy. The church increasing in power and riches, called on the arts of painting and sculpture, to add to the beauty and magnificence of her sanctuaries; riches and honors were showered on men whose genius added a new ray of grace to the Madonna, or conferred a diviner air on St. Peter or St. Paul; and as much of the wealth of Christendom found its way to Rome, the successors of the apostles were enabled to distribute their patronage over all the schools of Italy. Lanzi reckons fourteen schools of painting in Italy, each of which is distinguished by some peculiar characteristics, as follows: 1, the Florentine school; 2, the Sienese school; 3, the Roman school; 4, the Neapolitan school; 5, the Venetian school; 6, the Mantuan school; 7, the Modenese school; 8, the school of Parma; 9, the school of Cremona; 10, the school of Milan; 11, the school of Bologna; 12, the school of Ferrara; 13, the school of Genoa; 14, the school of Piedmont. Of these, the Florentine, the Roman, and the Bolognese are celebrated for their epic grandeur of composition; that of Siena for its poetic taste; that of Naples for its fire; and that of Venice for the splendor of its coloring.