O come, O come, Emmanuel, and ransom captive Israel, that mourns in lonely exile here until the Son of God appear. Rejoice! Rejoice! Emmanuel shall come to you, O Israel!

This favored Christmas carol is no carol at all.

It’s a hymn for the season of Advent — the liturgical season that is about so much more than simply preparing for Christmas. During these short four weeks, the Church has historically focused on our Lord Jesus Christ as the fulfillment of all prophecy and human yearning as she anticipates not only the celebration of his incarnation at Christmas but also as she waits in hope for his glorious return at the end of time.

The verses of O Come, O Come, Emmanuel are taken from seven ancient antiphons that the Church has used in her Evening Prayer liturgy since well before the ninth century. Every year, from Dec. 17 to 23, the Church’s liturgy enters a more intense and proximate preparation for Christ’s coming at Christmas. This shift is noticeable in the readings at Mass during these days, but also in the Church’s Liturgy of the Hours, specifically at evening prayer. Every evening during that week, the Church prays one of what have become known as the great “O Antiphons” before reciting Our Lady’s Magnificat canticle.

The O Antiphons invoke Our Lord using imagery taken from the Old Testament: O Wisdom From on High; O Lord of the House of Israel; O Root of Jesse’s Stem; O Key of David; O Radiant Dawn; O King of the Nations; and O Emmanuel. To these biblical images are added various pleas such as: “Come to teach us the path of knowledge!”; “Come to save us without delay!”; and “Come and free the prisoners of darkness!”

Each of these O Antiphons is a beautiful prayer in itself, but each also demonstrates exactly how the Church has come to understand Christ’s relationship to the promises and images of God so prevalent in the Old Testament.

O Wisdom From on High!

Isaiah prophesied that a shoot would sprout from the stump of Jesse. One of Jesse’s heirs would be a messianic figure and redeemer for Israel.

“The Spirit of the Lord shall rest upon him: a spirit of wisdom and of understanding” (Isaiah 11:1-2). Because Isaiah’s prophecies look forward so expectantly to the redemption of Israel and the whole world in the great promises of God, he is particularly the prophet of the season of Advent.

Christ, however, is more than the Anointed One. St. Paul told the Church in Corinth that “Christ [is] the power of God and the wisdom of God” (1 Corinthians 1:24). Christ is the Wisdom that the Book of Proverbs speaks of as God’s artisan and delight (Proverbs 8). The Eternally Begotten Son is always the delight of the Father and the Artisan through whom all things were made.

Perhaps a more poignant instance of a powerful Old Testament image of the divine is the Dec. 18 antiphon: O Lord of the House of Israel, giver of the Law to Moses on Sinai. The events recounted in the Book of Exodus are magnificently tremendous, from the Burning Bush to the parting of the Red Sea to the giving of the Law to Moses at a Mount Sinai covered in thunder and lighting.

The Church Fathers routinely noted Christ’s presence in God’s various manifestations to the Israelites. St. Justin Martyr recalled, “The same One, who is both angel and God, and Lord and man, and who appeared in human form to Abraham and Isaac, [also] appeared in a flame of fire from the bush and conversed with Moses.”

St. Gregory of Nyssa comments on the events of the desert — the clouds, the thunder and the tabernacle of God’s presence — “Taking a hint from what has been said by Paul, who partially uncovered the mystery of these things, we say that Moses was earlier instructed by a type in the mystery of the tabernacle which encompasses the universe.” This tabernacle, Christ the Son of God, he continues, “is in a way both unfashioned and fashioned, uncreated in pre-existence but created in having received this material composition.”

The pre-existing Eternal Son of God who is the perfect Image of God is also the presence of God in the flaming bush, on Mount Sinai and perfectly in his incarnation.

It is not surprising, therefore, that the Latin version of this antiphon begins with “O Adonai,” borrowing the Hebrew word God-fearing Jews speak when reading the Torah to avoid speaking the proper name of God himself — it is the name Lord, the name St. Paul tells the Philippians was bestowed on Christ because he did not deem equality with God something to be grasped, but rather emptied himself unto death (Philippians 2:6-11). Jesus Christ is Adonai. He is Kyrios. He is the Lord.

Finally, other O Antiphons identify Christ as the fulfillment of Israel’s greatness and human longing. He is the Oriens, the dawn that Isaiah promised would rise upon God’s chosen people (Isaiah 60:1-2). He is also the Root of Jesse. So he is not only the fulfillment, but the beginning, of the Israelite lineage.

He is the Creator and the One through whom David’s lineage came to be. So Christ is both the beginning and end of the promise to David. He is the Alpha and Omega. He is the One the Old Testament predicts will rule as King of all the nations.

The O Antiphons are much more than simple refrains to be chanted before Our Lady’s Magnifcat or to serve as verses in an Advent hymn. They reveal the mysteries of Christ already being revealed in the power and glory of God in the Old Testament.

St. Thomas Aquinas was right to insist that many of the great prophets of Israel had real and explicit prophetic knowledge of Jesus and his mysteries even though they lived hundreds of years before the Incarnation. “Abraham rejoiced that he was to see my day,” Jesus himself once preached. “He saw it, and he was glad” (John 8:56). Christ is active in Israel. He is in the Old Testament.

These great antiphons remind us that there is so much more to Advent than preparing for Christmas. They remind us that Christ is the focal point of salvation history, and, in fact, of all world history, because he is Emmanuel — “God with us.”

The wisdom of God is exactly such that the Lord creates us to be in relationship with him in order to bring light not only to our lives, but to the world. Every year the Church gives us these four weeks so that we might remember in an intense way what we should be living every day: in preparation, anticipation and joyful hope that the Lord will come to us and save us.

O Emmanuel, Our King and Giver of Law: Come to save us, Lord our God!

Dominican Father Thomas Petri is a professor of moral theology

at the Dominican House of Studies in Washington, D.C.