when we are dreaming, and as often happens, have a dim consciousness of the fact and try to wake, do we not say and do things which in waking life would be insane? May we not then sometimes define insanity as an inability to distinguish which is the waking and which the sleeping life? We often dream without the least suspicion of unreality: 'Sleep hath its own world', and it is often as lifelike as the other.
Charles Lutwidge Dodgson (aka Lewis Carroll)