Moses 2

 The Lord revealed to Moses that - 

"...I, God, said: Let there be light; and there was light.

4 And I, God, saw the light; and that light was good. And I, God, divided the light from the darkness.

5 And I, God, called the light Day; and the darkness, I called Night; and this I did by the word of my power, and it was done as I spake; and the evening and the morning were the first day."  (Moses 2:3–5)

And then He revealed - 

"...I, God, said: Let there be lights in the firmament of the heaven, to divide the day from the night, and let them be for signs, and for seasons, and for days, and for years;

15 And let them be for lights in the firmament of the heaven to give light upon the earth; and it was so.

16 And I, God, made two great lights; the greater light to rule the day, and the lesser light to rule the night, and the greater light was the sun, and the lesser light was the moon; and the stars also were made even according to my word.

17 And I, God, set them in the firmament of the heaven to give light upon the earth,

18 And the sun to rule over the day, and the moon to rule over the night, and to divide the light from the darkness; and I, God, saw that all things which I had made were good;

19 And the evening and the morning were the fourth day."  (Moses 2:14–19)

Obviously, the light spoken of on the first day is different from the light spoken of on the fourth day.

I believe the light spoken of first is the medium of the Light of Christ that provides life, righteousness, goodness, and truth.