The Lesson is taken from a Sermon by St. Leo the Pope
It is meet and right, dearly beloved, yea, it is the bounden duty of true godliness, to rejoice with full hearts upon those days which bear witness to the works of God's mercy; and to celebrate with honour the things which have been wrought for our salvation. Hereto are we called by the seasons of the year which continually return, and notably by this present season. For only a short time hath passed since that day whereon the Co-Eternal Son of God was born of a Virgin, and now is come the Feast of the Epiphany, hallowed by his Manifestation as The Lord.
In this same manifestation the good providence of God hath appointed a strong bulwark to our faith. For now, while in solemn worship we call to mind how the childhood of the Saviour was adored in its first infancy, we also are made to consider the historical evidence for the doctrine that Christ was born with very nature of man. For this is that which maketh the ungodly righteous, and sinners saints; to wit, the belief in the true Godhead and the true Manhood of the one and same our Lord Jesus Christ. Very Godhead, as touching which, he, being in the form of God, is equal to the Father from everlasting to everlasting; and very Manhood, wherein he, taking upon him the form of a servant, hath in these latter days been born Man.
For the strengthening of this our Faith, which we profess in the face of every false doctrine, the mercy of God hath made it come to pass that one of those peoples who dwell in the uttermost parts of the East, and excel in the skill of reading the stars, should see the sign of the birth of that Child who was to reign over all Israel. There appeared to the eyes of the Wise Men a new star of such surpassing beauty, as wrought in their minds, whilst they gazed thereon, such wonderment, that they could not do other than take it as an announcement of an event too important to be neglected.