The primary utterance of creation is “Let there be light,” and the first act of creation is the distillation of light, its separation from darkness.
The Midrash asks:
Where was light created from?
And the answer is whispered:
‘God cloaked Himself in a white shawl, and the light of its splendor shone from one end of the world to the other’ (Genesis Rabbah 3:4).
In other words, light, fundamentally, does not belong to this world.
It is, rather, an emanation of a different essence, from the other side of reality.”
From On Being Free, “The Motif of Light in the Jewish Tradition,” p. 181, by Rabbi Adin Steinsaltz