"Dreaming" is already pretty short. Also, it and "Creation" are to me the heart of the book and I would rather not try to summarize it. The full-length chapter is available on this website. Read Chapter on Dreaming
We perceive, and then we express that perception in some specific form. That is, we dream it. We understand the real, perceivable world by dreaming it. But when we decide that these dreams or some of these dreams are crucial, that they will save us, then they become "real." And the real world, the one we perceive, the place from where all dreams come from, disappears. Our dreams become our world, they become no longer something we have created, but something we have to answer to. When that happens, our dreams become shallow, they have no meaning, they are no longer connected to the real world and they are only assertion, they are only desire. Our love becomes a loveless dream.