Do not believe that a book is good, if in reading it thou dost not become more contented with thy existence, if it does not rouse up in thee most generous feelings.
He who attempts to make others believe in means which he himself despises is a puffer; he who makes use of more means than he knows to be necessary is a quack; and he who ascribes to those means a greater efficacy than his own experience warrants is an impostor.