The sages taught that God is not like any light that human beings have ever seen. The sun can be blocked by a cloud. A lamp can be extinguished by the wind. Even the stars fade when dawn approaches. But the light of God has no limit, no boundary, and no end.
The Talmud in Hullin (60a) records a teaching about the first day of creation. When God said "Let there be light" (Genesis 1:3), the radiance that burst forth was not the light of the sun — the sun would not exist for another three days. This was the Or HaGanuz (אור הגנוז), the Hidden Light, a brilliance so vast and so powerful that it illuminated every corner of the universe simultaneously.
The Midrash Hagadol on Deuteronomy (Va'etchanan) adds a startling detail: this primordial light was so intense that a person standing in one place could see from one end of the world to the other. Time and space collapsed in its presence. Past, present, and future were visible all at once. Adam, the first man, could see the entire sweep of history in that light — every generation, every event, every soul that would ever live.
But God saw that the wicked of future generations would misuse this light, bending it to corrupt purposes. So He hid it away, storing it for the righteous in the World to Come. The Maase Buch (No. 57) teaches that the righteous occasionally catch a glimpse of this Hidden Light on Shabbat (the Sabbath), when the extra soul descends and the boundaries between this world and the next grow thin.