Ramana Maharshi: Teachings of Self-Realization

"Everyone is aware of two things, namely himself, the seer, and the world which he sees; and he assumes that they are both real. But that alone is real which has a continuous existence. Judged by this test, the two, the seer and the spectacle, are both unreal: these two appear intermittently. They are apparent in the waking and dream state alone. In the state of deep sleep, they cease to appear. That is, they appear. That is, they appear when the mind is active, and disappear as soon as the mind ceases to function. Therefore, the two are but thoughts of the mind. There must be something from which the mind arises, and into which it subsides. That something must have a continuous, uninterrupted existence. That is, it must be the reality!"

-Ramana Maharshi