The Word of the Father, by whom all time was created, was made flesh and was born in time for us. He, without whose divine permission no day completes its course, wished to have one day for His human birth. In the bosom of His Father He existed before all the cycles of ages; born of an earthly mother, He entered upon the course of the years on this day.
The Maker of man became man that He, Ruler of the stars, might be nourished at the breast; that He, the Bread, might be hungry; that He, the Fountain, might thirst; that He, the Light, might sleep; that He, the Way, might be wearied by the journey; that He, the Truth, might be accused by false witnesses; that He, the Judge of the living and the dead, might be brought to trial by a mortal judge; that He, Justice, might be condemned by the unjust; that He, Discipline, might be scourged with whips; that He, the Foundation, might be suspended upon a cross; that Courage might be weakened; that Security might be wounded; that Life might die.
To endure these and similar indignities for us, to free us, unworthy creatures, He who existed as the Son of God before all ages, without a beginning, deigned to become the Son of Man in these recent years. He did this although He who submitted to such great evils for our sake had done no evil and although we, who were the recipients of so much good at His hands, had done nothing to merit these benefits.
Augustine, Sermons on the Liturgical Seasons