"You must distinguish between truth and falsehood; you must learn to be true all through, in thought and word and deed. In thought first; and that is not easy, for there are in the world many untrue thoughts, many foolish superstitions, and no one who is enslaved by them can make progress. Therefore you must not hold a thought just because many other people hold it, nor because it has been believed for centuries, nor because it is written in some book which men think sacred; you must think of the matter for yourself, and judge for yourself whether it is reasonable. Remember that though a thousand men agree upon a subject, if they know nothing about that subject their opinion is of no value."