The World as a Dream

Both inner and outer phenomena are like the appearances in a dream. Being inseparable from mind, they appear and develop in its space, are known through its clarity-awareness, and disappear again in its unlimited essence. One cannot say they are really existent, nor can one say they are non-existent. They are not both existent and non-existent, nor are they something else.

Neo: Have you ever had that feeling where you're not sure you're awake or still dreaming? 

Morpheus: Have you ever had a dream, Neo, that you were so sure was real? What if you were unable to wake from that dream? How would you know the difference between the dream world and the real world? 

Morpheus: You've been living in a dream world, Neo. 

Neo: This... this isn't real?  

Morpheus: What is real? How do you define real?

Maitripa: Phenomena are like a dream, empty of true nature. 

Lopön Tsechu Rinpoche: The most useful and most meaningful practice we can do is to understand that this life is only an illusion. Everything is like in a dream with no independent reality. To thus develop some understanding of Mahamudra is truly very important.
— The Intermediate States: The Bardo of Becoming 

Gendyn Rinpoche: It also helps to remember that the world we know is a world of illusion. It is a vision, a visible appearance that is the expression of confusion. Everything we perceive as the world around us, including ourselves, is only the product of all the tendencies associated with the five disturbing emotions. Dreams have exactly the same nature and in fact, the world and dreams are the same source of illusions or confused manifestation. The dream doesn't really exist, it is neither permanent nor real, and it can disappear at any time. If we believe that the dream is real, if we are attached to the idea that it is something that is really happening, we are tempted to manipulate what happens in the dream. We might want to obtain something, want to be happy, or want to avoid suffering. This is how we create suffering in the dream state.
  It is exactly the same in the case of waking world. If we recognize that it is only the natural expression of our past actions, we free ourselves of any attachment to the reality of the world. The experience we encounter while awake is called the Bardo of Birth and of Existence, an intermediate and temporary state made up of all the experiences of our life while awake. If we can purify our attachment to the reality of this world, we then have the possibility of detaching ourselves from the experiences met in the bardo of the dream. This training prepares us for the experience of death and everything that happens afterward when our consciousness moves toward the next rebirth. This training can free us from the experience of rebirth and can open us to perfect awakening.
  Discussing the meaning of the content of dreams is a waste of time since they are unreal.
— The World as a Dream 

Lama Ole Nydahl: Therefore, knowledge about mind's absolute and relative nature is essential. We need to understand that every experience is like a individual dream inside a collective one and only the experiencer really exists.