The light that was created on the first day, Adam saw in it from the end of the world… the Creator looked at the deeds of the generation of the flood and the generation of Babylon and saw that their practices were corrupt. He stood and concealed it for the righteous in the future.
Hence, before a person corrects the generation of the flood and the generation of Babylon within him, the hidden light is concealed from him. The generation of the flood is regarded as the heart, and the generation of Babylon is called “mind.” Since every person is comprised of the entire world, we attribute all the nations of the world to the evil in us.
Since the evil inclination is an angel, as our sages said, “He, Satan, is the evil inclination” (Baba Batra 16a), and our sages said that every angel is named only after his work, so when evil lusts awaken in a person, the evil inclination is called “the generation of the flood,” which is a Merkava [chariot/structure] for the generation of the flood.
Also, when evil thoughts awaken in a person, the evil inclination becomes a Merkava for the generation of Babylon. This is why the evil inclination is named after the generation of Babylon.
When those two general attributes are corrected, the hidden light is revealed because at that time he becomes righteous. This is the meaning of “concealed it for the righteous in the future,” meaning that only when there are righteous, this light is revealed and they begin to feel the delight and pleasure contained in Torah and Mitzvot [commandments].