The true answer to this argument for limiting freedom of thought will appear in due course. It was far from obvious. A long time was needed to arrive at the conclusion that coercion of opinion is a mistake, and only a part of the world is yet convinced. That conclusion, so far as I can judge, is the most important ever reached by men. It was the issue of a continuous struggle between authority and reason—the subject of this volume. The word authority requires some comment.
If you ask somebody how he knows something, he may say, "I have it on good authority," or, "I read it in a book," or, "It is a matter of common knowledge," or, "I learned it at school." Any of these replies means that he has accepted information from others, trusting in their knowledge, without verifying their statements or thinking the matter out for himself. And the greater part of most men's knowledge and beliefs is of this kind, taken without verification from their parents, teachers, acquaintances, books, newspapers. When an English boy learns French, he takes the conjugations and the meanings of the words on the authority of his teacher or his grammar. The fact that in a certain place, marked on the map, there is a populous city called Calcutta, is for most
