This is taken from a letter by Leo the Great, written to Flavian, Bishop of
Constantinople, in the year of our Lord 449.  It concerns the mystery of the
Incarnation, which is the keynote of today's noon time Holy Eucharist
Service.

Lowliness is assured by majesty, weakness by power, mortality by eternity.
To pay the debt of our sinful state, a nature that is incapable of suffering
was joined to one that could suffer.  Thus, in keeping with the healing that
we needed, one and the same Mediator between God and humankind, Jesus
Christ, Himself human (1 Timothy 2:5), was able to die in one nature, and
unable to die in the other.

He Who was true God was therefore born in the complete and perfect nature of
a true human being, whole in His own nature, whole in ours.  By our nature
we mean what the Creator had fashioned in us from the beginning, and took to
Himself in order to restore it.

For in the Saviour there was no trace of what the deceiver introduced and
humankind, being misled, allowed to enter.  It does not follow that because
He submitted to sharing in our human weakness He therefore shared in our
sins.

He took the nature of a servant without stain of sin, enlarging our humanity
without diminishing His Divinity.  He emptied Himself (Philippians 2:7);
though invisible He made Himself visible, though Creator and Lord of all
things He chose to be one of us mortals.  Yet this was the bowing-down in
compassion, not the loss of omnipotence.  So He Who in the nature of God had
created humankind, became in the nature of a servant, a human being Himself.

Thus the Son of God enters this lowly world.  He comes down from the throne
of heaven, yet does not separate Himself from the Father's glory.  He is
born in a new condition, by a new birth.

He was born in a new condition, for, invisible in his Own nature, He became
visible in ours.  Beyond our grasp, He chose to come within our grasp.
Existing before time began, He began to exist at a moment in time.  Lord of
the universe, He hid His infinite glory and took the nature of a servant.
Incapable of suffering as God, He did not refuse to be a human being capable
of suffering.  Immortal, He chose to be subject to the laws of death.

He Who is true God is also a true human being.  There is no falsehood in
this unity as long as the lowliness of humanity and the preeminence of God
coexist in mutual relationship.

As God does not change by His bowing down, so human nature is not swallowed
up by being exalted.  Each nature exercises its own activity, in communion
with the other.  The Word does what is proper to the Word, and flesh
fulfills what is proper to the flesh.

One nature is resplendent with miracles, the other falls victim to injuries.
As the Word does not lose equality with the Father's glory, so the flesh
does not leave behind the nature of our race.

One and the same Person - this must be said over and over again - is truly
the Son of God and truly the child of humanity.  He is God in virtue of the
fact that in the beginning was the Word, and the Word was with God, and the
Word was God (John 1:1).  He is human in virtue of the fact that the Word
was made flesh and dwelt among us (John 1:14).

Leo the Great, Epistola 28 ad Flavianum, 3-4.