the back of its Trinitarian and christological controversies. Tracing the concept from Tertullian and the “prosopographic exegesis” of the earliest Christians through the great controversies of the fourth and fifth centuries, Ratzinger suggests that Christian theologians have not always appreciated the important insights this tradition suggests. Rather than beginning from a generic notion of personhood, as Boethius and later Thomas Aquinas did, Christian theologians ought to begin from a more basic