No matter how vast your knowledge or how modest, it is your own mind that has to acquire it. It is only with your own knowledge that you can deal. It is only your own knowledge that you can claim to possess or ask others to consider. Your mind is your only judge of truth - and if others dissent from your verdict, reality is the court of final appeal. Nothing but a man's mind can perform that complex, delicate, crucial process of identification which is thinking. Nothing can direct the process but his own judgment. Nothing can direct his judgment but his moral integrity.
Ayn Rand (1999). “Ayn Rand Reader”, p.260, Penguin