Jean Jacques Rousseau:

Direct the attention of your pupil to the phenomena of nature, and you will soon awaken his curiosity; but to keep that curiosity alive, you must be in no haste to satisfy it. Put questions to him adapted to his capacity, and leave him to resolve them. Let him take nothing on trust from his preceptor, but on his own comprehension and conviction; he should not learn, but invent, the sciences. If ever you substitute authority in the place of argument, he will reason no longer; he will be ever afterwards bandied like a shuttle cock between the opinions of others.