Now Donatello had made for the Tribunal of Six of the Mercanzia that marble shrine which is now opposite to S. Michael, in the Oratory of Orsanmichele, and for this there was to have been made a S. Thomas in bronze, feeling for the wound in the side of Christ; but at that time nothing more was done, for some of the men who had the charge of this wished to have it made by Donatello, and others favoured Lorenzo Ghiberti. Matters stood thus as long as Donatello and Ghiberti were alive; but finally the said two statues were entrusted to Andrea, who, having made the models and moulds, cast them; and they came out so solid, complete, and well made, that it was a most beautiful casting. Thereupon, setting himself to polish and finish them, he brought them to that perfection which is seen at the present day, which could not be greater than it is, for in S. Thomas we see incredulity and a too great anxiety to assure himself of the truth, and at the same time the love that makes him lay his hand in a most beautiful manner on the side of Christ; and in Christ Himself, who is raising one arm and opening His raiment with a most spontaneous gesture, and dispelling the doubts of His incredulous disciple, there are all the grace and divinity, so to speak, that art can give to any figure. Andrea clothed both these figures in most beautiful and well-arranged draperies, which give us to know that he understood that art no less than did Donato, Lorenzo, and the others who had lived before him; wherefore this work well deserved to be set up in a shrine made by Donatello, and to be ever afterwards held in the greatest price and esteem.
Now the fame of Andrea could not go further or grow greater in that profession, and he, as a man who was not content with being excellent in one thing only, but desired to become the same in others as well by means of study, turned his mind to painting, and so made the cartoons for a battle of nude figures, very well drawn with the pen, to be afterwards painted in colours on a wall. He also made the cartoons for some historical pictures, and afterwards began to put them into execution in colours; but for some reason, whatever it may have been, they remained unfinished. There are some drawings by his hand in our book, made with much patience and very great judgment, among which are certain heads of women, beautiful in expression and in the adornment of the hair, which Leonardo da Vinci was ever imitating for their beauty. In our book, also, are two horses with the due measures and protractors for reproducing them on a larger scale from a smaller, so that there may be no errors in their proportions; and there is in my possession a horse's head of terra-cotta in relief, copied from the antique, which is a rare work. The Very Reverend Don Vincenzio Borghini has some of his drawings in his book, of which we have spoken above; among others, a design for a tomb made by him in Venice for a Doge, a scene of the Adoration of Christ by the Magi, and the head of a woman painted on paper with the utmost delicacy. He also made for Lorenzo de' Medici, for the fountain of his Villa at Careggi, a boy of bronze squeezing a fish, which the Lord Duke Cosimo has caused to be placed, as may be seen at the present day, on the fountain that is in the courtyard of his Palace; which boy is truly marvellous.