Read Old Books
"It is a good rule, after reading a new book, never to allow yourself another new one till you have read an old one in between…
Every age has its own outlook. It is specially good at seeing certain truths and specially liable to make certain mistakes. We all, therefore, need the books that will correct the characteristic mistakes of our own period. And that means the old books. All contemporary writers share to some extent the contemporary outlook… Nothing strikes me more when I read the controversies of past ages than the fact that both sides were usually assuming without question a good deal which we should now absolutely deny. They thought that they were as completely opposed as two sides could be, but in fact they were all the time secretly united—united with each other and against earlier and later ages—by a great mass of common assumptions…
People were no cleverer then than they are now; they made as many mistakes as we. But not the same mistakes. They will not flatter us in the errors we are already committing; and their own errors, being now open and palpable, will not endanger us. Two heads are better than one, not because either is infallible, but because they are unlikely to go wrong in the same direction. To be sure, the books of the future would be just as good a corrective as the books of the past, but unfortunately we cannot get at them."