Arise, shine, for your light has come,
and the glory of the Lord has risen upon you.
For darkness shall cover the earth,
and thick darkness the peoples;
but the Lord will arise upon you,
and his glory will appear over you.
Nations shall come to your light,
and kings to the brightness of your dawn.
(Church in Wales lectionary, from New Revised Standard Version)
I don't know about you, but most of the year I tend to go to bed when it's dark, and get up in the light. I remember my grandchildren from Peru arriving in August though and commenting on the oddity of going to bed while it was still light. But we can take it that normally most people go to bed when it's dark, and get up when it's light.
Isaiah, Chapter 60 promises that the people who have lived in darkness will live in the light when the Messiah arrives. For christians this happens with the birth of Jesus. This light comes from the glory of God and once we receive it we need to respond to it, in other words we need to arise and get to work, as it were!
This light has been seen before, in the light shining from the face of Moses after he spoke with God on the mountain, and later on Jesus on the mountain of transfiguration. When we see the light and accept that God has called us, we need to arise and start working. On this Epiphany Day we should begin to spread God's message to others through words or action.
Lord God,
who sent Your Son,
to be our Saviour
and the light of the world,
help us to accept that we
need to arise and respond
to Your call this day.
Amen.
You might like to look up the two examples mentioned above:
Moses: https://www.biblegateway.com/passage/?search=Exodus+34.29-35&version=NRSV
Jesus: https://www.biblegateway.com/passage/?search=Matthew+17.1-2&version=NRSV