From the Gelasian Sacramentary

It is, indeed, right that, with hearts raised up on high, we worship the divine mystery* by which the human condition, with the old and earthly law ceasing, is brought forth as a new and heavenly substance, miraculously restored, so that which is carried out by the great gift of God may be celebrated with the great joy of the Church. Through Jesus Christ our Lord, who lives and reigns with you and the Holy Spirit, ever one God, unto the ages of ages. Amen.

From Communion Prayers at Prime for Christmas morning. My terrible translation.

*Sc. the Incarnation.