C.S. Lewis on the importance of Old Books:

The only safety is to have a standard of plain, central Christianity ("mere Christianity" as Baxter called it) which puts the controversies of the moment in their proper perspective. Such a standard can be acquired only from the 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. If that is too much for you, you should at least read one old one to every three new ones.