“Papa, I have a surprise for you up in my room—can you come now?”

“Yes, Leonardo. What is it you have found now—not a better way to raise my grapes, I’ll wager!”

The elder da Vinci put his arm around the boy’s shoulder and went with him up to the door of his room.

“Wait here, Papa, until I say to come in.”

Leonardo unlocked his door, lifted the cloth from the shield standing on the easel and opened the shutter just a trifle so that a soft light filled the room.

“Papa—you can come in now.”

Piero entered—he had long forgotten the round piece of wood—and suddenly he froze in the middle of the room.

“Have mercy on me!” he said when he saw the horrible fire-breathing creature. In the dimness of the room, the monster and the murky cave from which it was emerging were terribly real. Piero actually started to back out of the room in fright, when Leonardo laid a hand on his shoulder.

“Papa, this work has served its purpose; take it away, then, for it has produced the intended effect.”

The shield was the talk of the house; it was set up and marveled at. As for Piero, he resolved to take it with him to Florence secretly and sell it, giving his peasant friend some cheap substitute that he would buy in the marketplace.