This Canticle was introduced in the Roman Breviary in 1970, and adopted by the 1979 Prayer Book to be used as the second Canticle in Morning Prayer on Tuesdays, Thursdays in Advent and Lent, and Saturdays.

O ruler of the universe, Lord God, great deeds are they that you have done, *
surpassing human understanding.
Your ways are ways of righteousness and truth,*
O King of all the ages.
Who can fail to do you homage, Lord, and sing the praises of your Name? *
for you only are the Holy One.
All nations will draw near and fall down before you, *
because your just and holy works have been revealed.
Glory be to the Father, and to the Son, and to the Holy Spirit; *
as it was in the beginning, is now, and ever shall be, world without end. Amen.

Taken from Revelation 15, this brief canticle praises God as the great King of all creation.  Its emphasis on God’s rule, and the falling down of the nations before him after his “just and holy works have been revealed” makes it especially suitable for use both in Advent (where its eschatological tone can stand out) and Easter (with its glorious emphasis on the divine victory).