By a ‘dream’ we mean something which is not real. What is Reality? That which does not disappear at any time.
Now, what is there in the waking state that does not disappear? Nothing. Therefore, everything objective, connected with the waking state, is unreal.
But what we have just called the unreal appears all the while. Yes. When the unreal appears as real we call it a dream. Therefore, the waking state is all a dream.
But there is one thing that does not disappear in any state – pure Consciousness, the Atma (Self).