Federzoni grinds the lenses for Galileo Galilei’s first telescope, a simple task that somehow makes him another of Galileo’s students (despite being older than either Andrea or the Little Monk). While a skilled workman and devoted friend, Federzoni lacks any kind of formal education. As such, he doesn’t speak Latin at all and he struggles to understand the complicated, Latinate arguments put forth by Galileo’s intellectual opponents. He is never embarrassed by these struggles, though, and he even seems comfortable engaging those opponents once Galileo has required them to make their arguments in Italian. Like Andrea and the Little Monk, Federzoni turns his back on Galileo after he recants his research.