In his second and last contribution to the “Controversy over the Comets,” Kepler stepped in as a “shield-bearer” to defend Tycho from Galileo’s attacks. As a champion of novel mathematical methods in science, Galileo might have had an incentive to make common cause with Grassi and Kepler against those who disparaged mathematical methods, but that would have required a more congenial attitude toward Tycho and his followers.