What it is...

...is a concept more than an event. Epiphany is the revelation of God in the person of Jesus Christ. Looking at some of the beautiful hymns of this season show us the big picture of one part of the life of Christ. Christmas hymns deal with the historical event of Christmas. Other hymns may focus on certain Biblical stories, laying out in four or five verses a healing story or a parable. Epiphany hymns seem to move from various events that help underline the truth that Jesus is God in the flesh.

You may sing about the visit of the Wise Men. In the next verse you'll sing of the baptism of Jesus. Then you will move on to the miracle at Cana and then one of the healing miracles. With 'big picture' strokes, the life of the God-Man Jesus is painted for us. Here's an example from LSB:

394 Songs of Thankfulness and Praise

1 Songs of thankfulness and praise,
Jesus, Lord, to Thee we raise,
Manifested by the star
To the sages from afar,
Branch of royal David’s stem
In Thy birth at Bethlehem:
Anthems be to Thee addressed,
God in man made manifest.

2 Manifest at Jordan’s stream,
Prophet, Priest, and King supreme;
And at Cana wedding guest
In Thy Godhead manifest;
Manifest in pow’r divine,
Changing water into wine;
Anthems be to Thee addressed,
God in man made manifest.

3 Manifest in making whole
Palsied limbs and fainting soul;
Manifest in valiant fight,
Quelling all the devil’s might;
Manifest in gracious will,
Ever bringing good from ill;
Anthems be to Thee addressed,
God in man made manifest.

4 Sun and moon shall darkened be,
Stars shall fall, the heav’ns shall flee;
Christ will then like lightning shine,
All will see His glorious sign;
All will then the trumpet hear,
All will see the Judge appear;
Thou by all wilt be confessed,
God in man made manifest.

5 Grant us grace to see Thee, Lord,
Present in Thy holy Word—
Grace to imitate Thee now
And be pure, as pure art Thou;
That we might become like Thee
At Thy great epiphany
And may praise Thee, ever blest,
God in man made manifest.

Text (sts. 1–5) and Music: Public domain
Created by Lutheran Service Builder © 2006 Concordia Publishing House.