Arguably the most influential theologian in the Latin West, Augustine of Hippo conventionally figures as the greatest ally, after the Bible, of Protestantism in Reformation Europe. Roman Catholics, however, also laid claim to Augustine as their chief witness—as the works of Peter Canisius (1521–1597), the most prominent catechist in the early Society of Jesus, attest. His Large Catechism adduces the authority of Augustine as “the truly Catholic doctor,” an authority Canisius repeatedly invokes to assert Catholic orthodoxy