i couldn't decide which of these quotes to put in here, so i'm posting them all...they're all by the same author, from the same book...but i find them thought-provoking:

"Perhaps a lunatic was simply a minority of one."

"For, after all, how do we know that two and two makes four? Or that the force of gravity works? Or that the past in unchangeable? If both the past and the external world exist only in the mind, and if the mind itself is controllable--what then?"

"But if there was hope, it lay in the proles. You had to cling on to that. When you put it into words it sounded reasonable; it was when you looked at the human beings passing you on the pavement that it became an act of faith."

--George Orwell, 1984