The Self is the only Truth, yet people have cultivated the habit of looking at it in completely the wrong way. All have conceived an incorrect perspective on it. Accepting the existence of Illusion forces us to deny the existence of Brahman which is eternal, and compels us to treat the ephemeral "I," as the only truth. Under the influence of this Illusion, we treat whatever is untrue as the "truth." If you want this delusion to vanish, be thoroughly acquainted with the fact that whatever is seen, conceived, or felt through the senses, is untrue, a mere appearance.
