In 1440, Lorenzo Valla famously unmasked the Donation of Constantine as the “bad penny” of Church historiography, a false coin masquerading as good currency. “We detect spurious coins,” Valla argued of biblical apocrypha, “we pick them out and reject them; shall we not detect spurious teaching? Shall we retain it, confuse it with the genuine and defend it as genuine?”1 Valla was neither the first nor the last writer in the fifteenth century to condemn the Donation of Constantine as specious; Nicholas of Cusa preceded him, Reginald Pecock followed him, and by the end of the century the document confirming Constantine’s magnificent gift to Pope Sylvester would prove destined for the ranks of famous forgeries. That early humanism should put to rest the myth of the Donation as one of its first iconoclastic gestures has proven a neat – indeed, too neat – encapsulation of the “break” that supposedly attends the transition of medieval to early modern.2 Here, philology unmasks forgery, skepticism counters timeworn creed, and the Donation collapses, a harbinger of future idols to fall during the Reformation.