Dreams demonstrate that our brains (and even rat brains) are capable of creating complex, immersive, fully convincing simulations. Waking life is also a kind of dream. Our consciousness exists, and is shown particular aspects of reality. We see what we see for adaptive reasons, not because it is the truth. Nerds are the ones who notice that something is off - and want to see what's really going on.

The View from Hell from an article recommended by asd.