“Light is the Genesis-creation of the world.
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