This one question “What do I know for certain?" is tremendously powerful. When you look deeply into this question, it actually destroys your world. It destroys your whole sense of self, and it's meant to. You come to see that everything you think you know about yourself, everything you think you know about the world, is based on assumptions, beliefs, and opinions, things you believe because you were taught or told that they were true. Until we start to see these false perceptions for what they really are, consciousness will be imprisoned within the dream state.