He must increase, viz, by the flocking of the people to Him, by the abundance and glory of His miracles, in adoration and worship, that the whole world may love and worship Him as Christ. So S. Cyril, to whom listen. "So long as the profundity of the æther is obscured by the shades of night, every one speaks with the greatest admiration of the morning star, as it shines with the full glory of its golden splendour. But when the sun is seen to hasten to his rising, and when his light somewhat illumines this our earth, the day star yields gradually to the greater luminary, and the words of John might not improperly he applied, He must increase, but I must decrease." Likewise S. Chrysostom says "Christ increases in that He by degrees manifests Himself by signs and miracles: not because He makes increase in virtue, - God forbid; for this would be the madness of Nestorius."
But I must decrease: not in virtue, Wisdom of Solomon , or merit. For in these John constantly increased until he received the crown of martyrdom, but as regarded the honour which he received in the people flocking to him. "I have fulfilled my office, now I will cease," as S. Chrysostom says of him. As a symbol of this, John was born shortly after the summer solstice, when the days begin to decrease; but Christ was born shortly after the winter solstice, when the days being at the shortest, begin to increase, as S. Chrysostom remarks, (Hom. de Nativ.), and others.
He who is from above, &c. He gives the reason why Jesus must increase; because He was from above, from heaven, out of the bosom of the Father, as the Only Begotten Son of God. Wherefore He is above all, not only me, John , but far above all angels and creatures whatsoever, forasmuch as He is the Creator and the Lord of all, and so by all to be worshipped and adored.