A man sees a great many things when he looks at the world for himself, and he sees them from many sides; but this method of learning is not nearly so short or so quick as the method which employs abstract ideas and makes hasty generalizations about everything. Experience, therefore, will be a long time in correcting preconceived ideas, or perhaps never bring its task to an end; for wherever a man finds that the aspect of things seems to contradict the general ideas he has formed, he will begin by rejecting the evidence it offers as partial and one-sided; nay, he will shut his eyes to it altogether and deny that it stands in any contradiction at all with his preconceived notions, in order that he may thus preserve them uninjured. So it is that many a man carries about a burden of wrong notions all his life long—crotchets, whims, fancies, prejudices, which at last become fixed ideas. The fact is that he has never tried to form his fundamental ideas for himself out of his own experience of life, his own way of looking at the world, because he has taken over his ideas ready-made from other people; and this it is that makes him—as it makes how many others!—so shallow and superficial.