There is a strange idea abroad that in every subject the ancient books should be read only by the professionals, and that the amateur should content himself with the modern books. . . . . .
. . . . Naturally, since I myself am a writer, I do not wish the ordinary reader to read no modern books. But if he must read only the new or only the old, I would advise him to read the old. And I would give him this advice precisely because he is an amateur and therefore much less protected than the expert against the dangers of an exclusive contemporary diet.
A new book is still on its trial and the amateur is not in a position to judge it. It has to be tested against the great body of Christian thought down the ages, and all its hidden implications (often unsuspected by the author himself) have to be brought to light. Often it cannot be fully understood without the knowledge of a good many other modern books.
If you join at eleven o'clock a conversation which began at eight you will often not see the real bearing of what is said. Remarks which seem to you very ordinary will produce laughter or irritation and you will not see why --— the reason, of course, being that the earlier stages of the conversation have given them a special point.
In the same way sentences in a modern book which look quite ordinary may be directed at some other book; in this way you may be led to accept what you would have indignantly rejected if you knew its real significance. 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.
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.