This comes from the hand of the Patriarch of Constantinople, St. Anatolius (d. 458) and is another early Christmas related hymn that we have.
In Bethlehem is He born,
Maker of all things, everlasting God!
He opens Eden’s gate,
Monarch of Ages! Thence the fiery sword
Gives glorious passage; thence
That severing mid-wall overthrown, the Powers
Of earth and Heav’n are one:
Angels and men renew their ancient league,
The pure rejoin the pure
In happy union! Now the Virgin-womb,
Like some cherubic throne,
Containeth Him, the Uncontainable:
Bears Him, Who while they bear
The Seraphs tremble: bears Him, as He comes
To shower upon the world
The fulness of His everlasting love.