A good task to set before yourself is to take every idea you agree with in a book and try to treat it as a “germ.” Tell yourself that you will develop it beyond the point where the author left off. Of course this will not always be possible. You will seldom succeed. But there is nothing like hitching your wagon to a star, and it will do no harm to set this up as an ideal.
A few miscellaneous problems remain to be considered.
How should we deal with authors with whom we disagree fundamentally? Herbert Spencer relates that he twice started Kant’s Critique of Pure Reason, but disagreeing fundamentally with the first and main proposition he ceased reading. Now to do this is to give an author too much credit for consistency. For even if every other proposition he sets forth is ostensibly a corollary from his leading one, some of them will contain much truth. It is impossible to be consistently wrong. Add to this the possibility that the author may be right on his first proposition after all. However, no book with a viewpoint radically different from our own should be used as a main text, for we would get little benefit from it. If the book is by an obscure author we may safely lay it aside altogether. But if it is by so famous and so bepraised a philosopher as Kant we should at least glance through the entire volume for suggestions.
How many times ought we to read a book? I have already partly answered this in formulating the law of diminishing returns. Few books are worth re-reading. Rather than read one book twice on any given subject it will most often be more profitable to read another book on it. For the second will not only serve as a review of previous knowledge, but will furnish you with new ideas, different aspects and new problems.
Certain books, however, can never be replaced by others. They occupy this position either because they deal with a subject not elsewhere dealt with or because they take an entirely novel aspect, or solely because they are the works of supreme genius, for while the main conclusions reached in works of this last type may be found elsewhere, the manner of thinking can never be. These books should be read twice. The main text-book selected on any subject will usually be chosen because it is the best and most comprehensive work on that subject. For this reason it should be read a second time even if such reading is only of the hop, skip and jump variety.
We should not re-read a book immediately upon the first completion but should always allow a long interval to elapse. There are several reasons for this. After an interval we acquire perspective; we are in a position to know whether a book has done us any good and just about how much. We may find after this interval that a work of which we thought quite highly at the time of reading has really not helped us appreciably either in thought or action. We may find that we have outgrown the need of it. Even if we finally decide to re-read we shall find the wait of immense help to our memory. If we re-read a book after an interval of six months, three years after our second reading we will remember its contents much better than if we had read it three times in unbroken succession. Add to this that in the lapse of time we shall have forgotten most of the work, and shall therefore approach it the second time with greater interest than if it were still fresh in mind; that our experience, reading and thinking in the meantime will make us see every sentence in a different light, enabling us to judge our own marginal criticisms (if we have made any) as well as the book, and the advantage of waiting cannot be doubted. I do not believe it will ever be necessary to read a book more than twice, that is, so far as thought and knowledge are concerned. With books read for their style or for mere amusement the case is different.
How long should one read at a sitting? Some men find that their thought is choked by reading. Some find it stimulated. But results vary according to the length of time reading is carried on. Reading for very long periods at a stretch often deadens original thought. The writer finds that he nearly always derives benefit from reading for short periods, say ten or fifteen minutes. This is in some measure due to the increased concentration which short periods allow. On the other hand, some people find that a certain momentum is acquired during long reading periods. The reader can only experiment to find how long a period best suits his individual case.
How about concentration? This has been considered in relation to independent thinking, but in reading the problem is somewhat different. In thinking our task is to choose relevant associates. In reading the associates are chosen for us. Our task is to stick to them, instead of following the associates which occur to us either from what we read or from sights and sounds about us. But associates which occur to us from what we read are of two kinds: relevant and irrelevant, and the former should of course be followed out. This however should be done deliberately, in the manner I have previously indicated, and when the vein of suggested thought has been exhausted we should bring attention back to our book. The problem of concentration is not a very serious one in reading. It may sometimes be difficult to concentrate on a book. But it is infinitely easier than concentrating on a problem by unaided independent thought.