The light that was to enlighten the whole world was about to shine upon it, driving away the thick, loathsome gloom of death and ignorance in which the author of darkness had enveloped it.

And since that light was eternal and incomprehensible, it was preceded by a number of shorter-lived luminaries whose rays were more readily intelligible to men.

I refer to our fathers of the Old Testament through whose virtue, teaching, and example the Lord’s faithful people were enlightened and instructed and the shadows of their age-old blindness dispersed, so that, if not entirely, at least in part, they would be able to recognise the light when it shone upon them.

Not from themselves, nor from any other man did these lesser luminaries derive their light, but from the Supreme Light itself.

They were the ones who followed the path of God’s commandments, some prior to the law, some under the law, some in the days of the judges, the kings, or the prophets but all heralding the mysteries of our Lord’s birth, passion, resurrection, and ascension.

And after them all came John, the Lord’s forerunner, a beacon whose clear light led the people to the one whom the patriarchs had proclaimed and the prophets foretold.

[…] The Gospel tells us how John was filled with the Holy Spirit while still in his mother’s womb and leapt for joy in the presence of the mother of his Lord, moved by no natural impulse but by the stirring of divine grace.

Later John bore witness to Christ the Lord in the words: Behold the Lamb of God, who takes away the sins of the world!

And Christ in his own preaching gave testimony to John, saying: Among the sons of women there has never arisen a greater than John the Baptist.

Calling him the greatest among those born of women, he drew attention to John’s constancy and austere manner of life and declared him to be a prophet and more than a prophet.

By his own divine power Christ endowed John with privileges and graces in excess of all others, describing him, through the lips of the prophet Malachi, as the messenger who was to go before him to prepare the path of his salvation.

Odilo of Cluny (c.962-1048/1049): Sermon 10, PL 142, 1019-1020, from the Monastic Office of Vigils, Wednesday of the First Week of Advent Year I