In the preceding poem Saint John of the Cross evoked God's plan: the Redemption and the accomplishment of the Covenant. He expressed in biblical language where the Covenant is alluded to as a wedding between God and humankind. And for this, the Bridegroom must take on the likeness of the Spouse; he must "manifest himself in mortal flesh."
At present, John of the Cross conjures up the decisive moment when the Bridegroom becomes incarnate:
Then He called an Archangel
known as Gabriel
and sent him to a Virgin
known as Mary,
at whose consent
the mystery took place
in whom the Trinity
clothed the Word with flesh.
And although Three performed the deed,
it was done through the one;
and the Word lived incarnate
in Mary's womb.
And He was had only a Father
now had a Mother too,
but she was not like others
who are conceived by man.
From her own flesh
He received His flesh,
so He is called
the Son of God and of man.
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Saint John of the Cross, Ballad 8
Taken from "The Poems of Saint John of the Cross, English Versions and Introduction by Willis Barnstone", New Directions Book, 1972