There is a Kabbalistic view that the light of the first day was not the same light that emanates from the sun and the moon. The light of the first day was a "sourceless" light which was spiritual in nature. God, realizing that man would not be able to live up to the spiritual nature of such a light, stored it away and it was set aside for the future use of the righteous. In its stead God created the sun and the moon, which, according to the Sages, give us but a fraction of the original, true, light.
