The Feast of the Epiphany, now observed twelve days after Christmas, is in fact the older of the two observances. As early as the fourth century, this day was marked to celebrate the Incarnation, including the Nativity, the visit of the three magi, the baptism of Christ in the Jordan, and even the anniversary of Jesus's first miracle at Cana. Now, of course, we've broken those all up into different occasions, with Christmas overshadowing them all.
The season of Epiphany retained the other observances of the Incarnation, those examples of Christ showing his divine nature to the world around him, leaving the date of January 6 for the story of the sages from the East (but signifying the nations of the world) following a brilliant star which guided them to the wondrous birth in Bethlehem.
This particular hymn also dates from the fourth century, though it was not a part of the Catholic Epiphany liturgy until 1570, following the Council of Trent. Marcus Aurelius Clemens Prudentius only became a Christian poet late in life, after careers as a lawyer and judge. This text (O sola magnarum urbium) begins at line 77 of a much longer work, Quicumque Christum quaeritis. It has been translated into English several times; this one is based on a version by Edward Caswall, altered by the editors of Hymns Ancient and Modern in 1861 (where it was first matched to this tune).
Earth has many a noble city;
Bethlehem, thou dost all excel;
Out of thee the Christ from heaven
Came to rule o'er Israel.
Fairer than the sun at morning
Was the star that told his birth,
To the world its God announcing
Seen in fleshly form on earth.
Eastern sages at his cradle
Make oblations rich and rare;
See them give, in deep devotion,
Gold and frankincense and myrrh.
Sacred gifts of mystic meaning:
Incense doth their God disclose,
Gold the promised reign proclaimeth,
Myrrh his sepulcher foreshows.
Jesus, whom the nations worshipped
At thy glad Epiphany,
Unto Thee, with the Creator
And the Spirit, glory be.
Aurelius Prudentius, 4th cent.
tr. Edward Caswall, 1849; alt.
Tune: STUTTGART (22.214.171.124.)
Psalmodia Sacra; 1715
adapt. Henry J. Gauntlett, 1861
One Year Ago: We Too May Seek That Cradle