In the Great Perfection (Dzogchen) teachings, the issue is always whether or not we recognize our true nature and understand that the reflections of that nature manifest as experience. The dream is a reflection of our own mind. This is easy to believe after we wake up, just as the Buddhas know—after they are enlightened—that the entities and objects of samsara are illusory. And just as it takes practice to recognize the illusory nature of dream while asleep, we must practice to realize the illusory nature of waking life.
—The Tibetan Yogas of Dream and Sleep by Tenzin Wangyal Rinpoche, page 53