What was the light of the first day of creation? In the Genesis account, the sun and stars are created on the fourth day:

Gen 1:14  And God said, &quot;Let there be lights in the expanse of the heavens to separate the day from the night. And let them be for signs and for seasons, and for days and years,
Gen 1:15  and let them be lights in the expanse of the heavens to give light upon the earth.&quot; And it was so.
Gen 1:16  And God made the two great lights—the greater light to rule the day and the lesser light to rule the night—and the stars.]
Gen 1:17  And God set them in the expanse of the heavens to give light on the earth,
Gen 1:18  to rule over the day and over the night, and to separate the light from the darkness. And God saw that it was good.

However, light is created on the first day:

Gen 1:3  And God said, &quot;Let there be light,&quot; and there was light.
Gen 1:4  And God saw that the light was good. And God separated the light from the darkness.

So, from the perspective of a literal reading of this account, how is this reconciled?  Is light created twice?  How could there be light without the sun and stars?
Revelation 21:23 answers this rather directly.  In imagining the new heaven and the new earth, it says:


  The city does not need the sun or the moon to shine on it, for the glory of God gives it light, and the Lamb is its lamp.


John 1:5 concurs, saying:


  This is the message we have heard from him and declare to you: God is light; in him there is no darkness at all.


Thus being capable of its own luminesence, there is thus nothing to contradict the possibility that God himself was the source of the light.  There is also no need to take such an idea - that God is the light, and God speaking the Light into existence is creating himself, and contradict the notion that Jesus himself was not created.  Indeed, since Jesus was not created, he was eternal.  As John 1:1 indicates, In the beginning was the Word, and the Word was with God, and the Word was God.  Being thus present, God's glory would have been assumed to be there.  And, just like a lit candle, if its there, there will be light.

Rather, prior to his speaking, there is nothing to suggest that there was even a space into which his Light could shine.  As such, in "creating the light," he simply created the space in which his own light - the emanation of His glory - could be beheld. 

The "Shekinah Glory" of the Lord is often compared to a bright light, so this is not altogether an unreasonable assumption.  

Additionally, Isaiah 6:2 speaks of the seraphim as follows:


  Above him were seraphim, each with six wings: With two wings they covered their faces, with two they covered their feet, and with two they were flying.


If they are covering their faces, it would also be consistent with a brightness emanating from the Glory of God.

And, finally, as we are reminded every Christmas that when the angels appeared to the shepherds,


  "An angel of the Lord appeared to them, and the glory of the Lord shone round about them, and they were terrified.


In seemingly every instance, the glory of the Lord shines, thus producing its own light.