Guglielmo used only two kinds of colour for the shading of such glass as he proposed to subject to the action of fire; one was scale of iron, and the other scale of copper. That of iron, which is dark, served to shade draperies, hair, and buildings; and the other, that of copper, which produces a tawny tint, served for flesh colours. He also made much use of a hard stone that comes from Flanders and France, called at the present day hematite, which is red in colour and is much employed for burnishing gold. This, having first been pounded in a bronze mortar, and then ground with an iron brazing instrument on a plate of copper or yellow brass, and tempered with gum, works divinely well on glass. When Guglielmo first arrived in Rome, he was no great draughtsman, although he was well practised in every other respect. But having recognized the need of this, he applied himself to the study of drawing, in spite of his being well advanced in years; and thus little by little he achieved the improvement that is evident in the windows that he afterwards made for the Palace of the said Cardinal at Cortona, and for the other without the city, in a round window that is in the aforesaid Pieve, over the facade, on the right hand as one enters the church, wherein are the arms of Pope Leo X, and likewise in two little windows that are in the Company of Gesu, in one of which is a Christ, and in the other a S. Onofrio. These are no little different from his early works, and much better. Now while Guglielmo, as has been related, was living in Cortona, there died at Arezzo one Fabiano di Stagio Sassoli, an Aretine, who had been a very good master of the making of large windows. Thereupon the Wardens of Works for the Vescovado gave the commission for three windows in the principal chapel, each twenty braccia in height, to Stagio, the son of the said Fabiano, and to the painter Domenico Pecori; but when these were finished and fixed in their places, they gave no great satisfaction to the Aretines, although they were passing good and rather worthy of praise than otherwise. It happened at this time that Messer Lodovico Belichini, an excellent physician, and one of the first men in the government of the city of Arezzo, went to Cortona to cure the mother of the aforesaid Cardinal; and there he became well acquainted with our Guglielmo, with whom, when he had time, he was very willing to converse. And Guglielmo, who was then called the Prior, from his having received about that time the benefice of a priory, likewise conceived an affection for that physician, who asked him one day whether, with the good will of the Cardinal, he would go to Arezzo to execute some windows; at which Guglielmo promised that he would, and with the permission and good will of the Cardinal he made his way to that city. Now Stagio, of whom we have spoken above, having parted from the company of Domenico, received Guglielmo into his