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. * * * * * The plan of reading I have laid out is merely suggestive. What I chiefly wanted to show was that all books cannot be treated alike, that we cannot lay down dogmatic inflexible rules to apply to every volume. Our method of reading will vary with the nature of a book or of the subject it treats. It will depend upon the books we have already read and even upon the books we contemplate reading later. The good you get out of reading will depend entirely on how you allow it to affect you. If every book you read suggests more problems, gives you worth-while questions and topics to think about in spare moments, enriches your intellectual life and stimulates your thought, it is performing its proper function. But if you read solely to answer problems you cannot answer for yourself, if every time you are puzzled about anything you run to a book to have it explained, and accept without question the explanation there given; in short, if you use your reading to save yourself from thinking, you had better stop reading altogether. Smoking is a far less harmful form of dissipation. I have not yet definitely indicated the ratio which time given to reading should bear to time devoted to thinking. I have avoided this because of the many factors to be taken into account. But if the reader happens to have a spare hour to devote to the improvement of his mind, he will not go very far wrong if he gives thirty minutes to reading and thirty minutes to thinking. His thinking may be on the subject he has read, or part of it may be on other problems. That is not so important. But the reader must not imagine that his thinking need be restricted to these thirty minutes or any other thirty minutes. The glorious advantage of thinking is that it can be fitted in at any odd moment. The entire apparatus for carrying it on is always with you. You do not even need a book for it. I remind the reader of this at the risk of repeating myself. * * * * *