Lead was a costly thing in the Middle Ages. It was sometimes used for roofing purposes, as well as for gutter-pipes and drain-pipes, because it will not rust as iron will, and can easily be worked. Alan had played about that rubbish heap, and he knew that there were lumps of lead among the wood-ashes and crumbled stones. Much marveling, he led the artist to the pile of rubbish that had been thrown over the wall, and helped to dig out the precious bits of metal. Then the fire was lighted once more, and triumphantly Angelo melted the lead and purified it, and rolled it into sheets, and cut it into strips. "Now," he said one morning, "we are ready to begin. I shall make a medallion which can be set in a great window like embroidery on a curtain. It shall be a picture--of what, my son?" His dark eyes were very kind as he looked at the boy's eager face. The question had come so suddenly that Alan found no immediate answer. Then he saw his pet lamb delicately nibbling at a bit of green stuff which his mother held out to it as she stood in her blue gown and white apron, her bright hair shining under her cap. "I wish we could make a picture of her," he said a little doubtfully. Angelo smiled, and with a bit of charcoal he made a sketch on a board. Alan watched with wonder-widened eyes, although he had seen the old man draw before. Then they went together into the little room which had seen so many surprising things, and the sketch was copied on the broad wooden bench which they had been using for a table. Then holding one end of a piece of string in the middle of the lamb's back, Angelo slipped the charcoal through a loop in the other end, and drew a circle round the whole. Around this he drew a wreath of flowers and leaves. Then he laid the white glass over the lamb and drew the outline just as a child would draw on a transparent slate, putting in the curls of the wool, the eyes and ears and hoofs, with quick, sure touches. This done, he set the white glass aside, and drew Dame Cicely's blue gown and the blue of a glimpse of sky on the blue glass. The green of the grass and the bushes was drawn on the green glass, and the roses on the red, and on the yellow, the cowslips in the grass. When all these had been cut out with a sharp tool, they fitted together exactly like the bits of a picture-puzzle, but with a little space between, for each bit of the picture had been drawn a trifle inside the line to leave room for the framework.