Reginald Pecock (ca. 1390-1459) was the cause of a great scandal for the late medieval Church. In the autumn of 1457, the bishop of Chichester confessed, among other things, that the Church itself could err in matters of faith. On the eve of the Protestant Reformation, however, a high-ranking cleric making such a claim was both embarrassing and a big liability. The Book of Faith, finished just months before Pecock's disgrace, is the only record of...