Our Saviour, dearly Beloved, was born this day. Let us rejoice. Sadness is not becoming upon the Birth Day of Life Itself, which, now that the fear of death is ended, fills us with gladness, because of our own promised immortality. No one is excluded from sharing in this cheerfulness, for the reason of our joy is common to all men. Our Lord, the Conqueror of sin and death, since there was no one free from servitude, came that He might bring deliverance to all.
(From a Christmas sermon of Pope Leo the Great)