t figures,
those in the other figures being darker in proportion as they
receded; in which point he was a rare and truly excellent master.
Moreover, he showed very good judgment in the painting of his
figures; whereby he executed them with such unity, that they fell
back into the distance little by little, in such a way that they did
not cling either to the buildings or to the landscapes, and had the
appearance of being painted on panel, or rather in relief. He showed
invention and variety in the composition of scenes, making them
rich and well grouped; and he rendered easy the process of making
such pictures as are put together out of pieces of glass, which was
held to be very difficult, as indeed it is for one who has not his
skill and dexterity. He designed the pictures for his windows with
such good method and order, that the mountings of lead and iron,
which cross them in certain places, were so well fitted into the
joinings of the figures and the folds of the draperies, that they
cannot be seen--nay, they gave the whole such grace, that the brush
could not have done more--and thus he was able to make a virtue of
necessity.

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