The Underground Man claims he despises the notion of the crystal castle because he is unable to stick his tongue out at it. By this, he implies that the crystal palace's blind, uncompromising confidence in reason undermines the significance of individuality and personal freedom. He also rejects the idea of a perfect world because nothing can escape its fate. Lao Tzu said, "He who knows himself knows what he should do, but who knows what he should do does not know himself." This means that if you want to find out what is true for you, then you have to look inside yourself and see. The Underground Man appears in William Blake's epic poem The Marriage of Heaven and Hell. It pictures him as a visionary who has seen beyond the darkness of this world to the light and love that lie deep within humanity. Through his words, we are shown the way forward with hope for mankind. He is a symbol of individual conscience standing up against authority, even when this means suffering punishment. In literature, the underground man is usually a human being who lives either alone or in small groups in remote places. They often possess some kind of wisdom that others find impossible to understand. Sometimes they are considered mad because no one wants to listen to their warnings.