In the imperishable and infinite Highest Brahman, wherein the two, knowledge and ignorance, are hidden, the one, ignorance, perishes, the other, knowledge, is immortal; but he who controls both, knowledge and ignorance, is another.

In plain words: In the highest Brahman, the endless and undying reality, both knowledge and ignorance are hidden. Ignorance passes away, but knowledge lasts forever. The one who rules over both is someone else: God.