This Advent, I’ve been reading Contra Nestorianos et Eutychianos by Leontius of Byzantium (485-543). Leontius was a sixth century theologian, who was instrumental in the development of the doctrine of the incarnation, especially in the controversies that led to the Fifth Ecumenical Council, the Second Council of Constantinople (553). As its title suggests, this book tackles the opposite errors of Nestorianism (which split Christ into two persons) and Eutychianism (which merged the two natures of Christ into one). Leontius argues that these two heresies are actually opposite forms of the same error: docetism (from dokeo, to seem or appear). In Nestorianism, Christ only seems to be divine, while in Eutychianism, he only seems to be human. In place of these errors, Leontius defends the Chalcedonian doctrine of Christ: Christ is one person (indeed, a divine person, one of the Holy Trinity) with two natures: the nature of God and the discrete human nature that he assumes and personalizes (enhypostasis) in the incarnation. These two natures are united in the one person of the Son and yet they retain their distinct properties.
One of the ways that Leontius seeks to explain this doctrine is by appeal to the unity of two distinct substances in an ordinary human person: body and soul. Leontius acknowledges, however, that this analogy isn’t perfect. After spending several pages exploring the analogy and its usefulness and limitations, he argues that all analogies simply give us “faint impressions of the truth that is above all examples.” He says his aim is “giving drink to all lovers of truth in a small container.” That, I think, is an beautiful description of all doctrinal apparatuses, terminologies, and analogies: they simply give us a little cup to hold what is ultimately uncontainable: the transcendent truth of the mystery of Christ.