Because, from His essence, God burned with the love of uniting Himself
to man, it was necessary that He should cover Himself around with a
body adapted to reception and conjunction. He therefore descended and
assumed a human nature in pursuance of the order established by Him
from the creation of the world. That is, He was to be conceived by a
power produced from Himself; He was to be carried in the womb; He was
to be born, and then to grow in wisdom and in love, and so was to
approach to union with His Divine origin. Thus God became Man, and Man
God.
--_True Christian Religion, n._ 838