The canticle Great Indeed Is the Mystery of Godliness (A Song of Christ’s Appearing) was used in the Roman Liturgy of the Hours in Evening Prayer on Transfiguration.
Great indeed is the mystery of godliness:
He was manifested in the flesh,
vindicated by the Spirit,
seen by angels,
proclaimed among the nations,
believed on in the world,
taken up in glory.
Glory be to the Father, and to the Son, and to the Holy Spirit:
as it was in the beginning, is now, and will be forever. Amen.
Source: The Holy Bible: English Standard Version, 1 Timothy 3:16
you so loved the world
that you gave your only Son
to reconcile the earthly with the heavenly;
Move us to love you above all things,
that we love our friends in you,
and our enemies for you;
through your Son, Jesus Christ our Lord.
Source: Freely modified from Mozarabic Collects, ed. Rev. Chas. R. Halle, New York, 1881, p. 21 #2 (Sexagesima)
“O God, you so loved the world…” is a reference to John 3:16
“to reconcile the earthly with the heavenly” is a reference to 2 Corinthians 5:19, Colossians 1:20
“Move us to love you above all things” is a reference to Deuteronomy 6:5, Matthew 22:37, Mark 12:30, Luke 10:27