O admirabile commercium creator generis humani animatum corpus sumens de virgine nasci dignatus est et procedens homo sine semine largitus est nobis suam deitatem.
O wonderful exchange: the creator of humankind took on a living body, merited to be born of a virgin, and, being born as a man without seed, gave us his deity.
One of the O Antiphons is suited equally to the Annunciation (the March 25 commemoration of the conception of Jesus Christ inside of his mother Mary) as to singing during the time just after Christmas. It is the first O Antiphon alphabetically in its Latin text, and so reading it at it the beginning of Advent makes a logical sense.
We have begun a season of exchanges, a kind of directional action that is common enough in our normal lives. Foreign exchange of money for other money when we travel for work or go on vacation to another country. The gift exchanges of social obligation, workplace fellowship, friendly sincerity. Exchanges of one place for another when we travel to visit family during the longue durée of the extended holiday period. And all of us reading this live in the permanent shadow of the Columbian Exchange that brought horses and bees and measles to Mexico in return for coffee, gold, slaves, chocolate, potatoes, and slaves to Europe.
O admirabile commercium is a capsule of three words that contain some of the potent truths about the incarnation as an exchange of another kind. The incarnation is the teaching that in the person of Jesus Christ the fulness of the eternal world-creating God became joined permanently, unbreakably, inexplicably, with the fulness of humanity: God exchanging incorporeality for a specific body that was born like every other human baby from a particular woman in a given place. The exchange went reciprocally but not transactionally in the other direction, too: largitus est nobis suam deitatem: “God gave us his deity.”
The Wonderful Exchange confers on every human person a permanent dignity that nothing can take away—age, actions, station, illness, immigration status, “gloomy doubts and faithless fear”—none can change God’s chosen identity with us and all whom we meet by choice or chance.
If this principle confers on each of us duties of respect and reverence toward those around us—the same respect and reverence that we would give to God—it does so along the lines Frank Weston of Zanzibar explained in a famous 1923 sermon: “if God leapt a gulf for you, I suppose that you can leap gulfs for God.”
Advent emerges then as a season of jumps: from God to us, from us to God, from me to you, and from each of us in sincerity toward anyone who differs from us.
If you’d like to listen to O admirabile commercium in music that has nourished souls before us for half a thousand years, Handl, Josquin Desprez, William Byrd, and Hans Leo Hassler are all free and brief.
—For background on this Advent reflection, see Slouching toward Bethlehem in 2019.
A Pennsylvanian in Connecticut (and often other places), Richard Mammana is a father, author, reviewer, archivist, web developer and ecumenist. He is the founder of anglicanhistory.org.