DionysiosThe time is come to sing the God of many Names, as “Sovereign Lord,” and as “Ancient of days.”

For He is called the formerby reason that He is an all-controlling basis,

binding and embracing the whole, and establishing and supporting, and tightening, and completing the whole,

continuous in itself, and from itself, producing the whole, as it were from a Sovereign root, and turning to itself the whole, as to a sovereign parent stock,

and holding them together as an all-embracing basis of all, securing all the things embraced, within one grasp superior to all,

and not permitting them, when fallen from itself to be destroyed, as moved from an all-perfect sanctuary.

But the Godhead is called Sovereign, both as controlling and governing the members of His household, purely, and as being desired and beloved by all,

and as placing upon all the voluntary yokes, and the sweet pangs of the Divine and Sovereign, and in dissolvable love of the Goodness itself.

But Almighty God is celebrated as “Ancient of days” because He is of all things both Age and Time, and before Days, and before Age and Time.

And yet we must affirm that He is Time and Day, and appointed Time, and Age, in a sense befitting God, as being throughout every movement unchangeable and unmoved, and in His ever moving remaining in Himself, and as being Author of Age and Time and Days.

Wherefore, in the sacred Divine manifestations of the mystic visions, He is represented as both old and young;

the former indeed signifying the “Ancient” and being from the beginning, and the latter His never growing old; or both teaching that He advances through all things from beginning to end.

[…] The Oracles…do not always merely call all the things absolutely unoriginated and really everlasting, eternal, but also things imperishable and immortal and unchangeable.

[…] The Word of God says that even we, who are bounded here by time, shall partake of Eternity, when we have reached the Eternity which is imperishable and ever the same.

But sometimes eternity is celebrated in the Oracles, even as temporal, and time as eternal. … It is necessary then to suppose that things called eternal are not absolutely co-eternal with God, Who is before Eternity.

[…] But Almighty God we ought to celebrate, both as eternity and time, as Author of every time and eternity, and “Ancient of days,” as before time, and above time, and as changing appointed seasons and times;

and again as being before ages, in so far as He is both before eternity and above eternity and His kingdom, a kingdom of all the Ages. Amen.

Denys the Areopagite (late 5th-early 6th century?): On the Divine Names 10, 1-3.