The man who desires to study any subject is commonly advised to read first a small “introductory” book, then a larger one, and finally the largest and most authoritative volumes. The trouble with this practice is that you will have to study each book in turn. If you take up the most thorough book first you need merely glance through the smaller books, for the chances are that they will contain little that is new to you, unless they happen to be more recent. The only justification for reading a small book first is that the larger books are apt to be technical and to assume a certain knowledge of the subject. However, _the_ authoritative treatise or treatises on a subject usually refer far less to the smaller books than the smaller books do to them. Any greater depth of thought which the larger works may possess can be made up for by increased concentration on the part of the reader. Of course if a man does not intend to master a subject thoroughly, but only to get some idea of its broad outlines, the case is different. He would then be justified in reading a small work. Another advantage of beginning a subject with the study of a comprehensive and authoritative volume or main textbook, is that you avoid confusion. The man who has mastered one foreign language, say French, will always find his knowledge of great benefit to him for the study of another language, such as Spanish. But any one who has begun at about the same time the study of two or more foreign languages must remember his confusion, and how his vague knowledge of one tongue hindered him in the acquisition of the other. So with reading. When we peruse a book in the usual casual way we do not master it. And when we read a book on the same subject immediately after it, the different viewpoint is liable to cause bewilderment and make us worse off than before the second book was started. We do not like to devote a lot of time to one book, but would rather run through several books in the same time, believing that we thereby gain more ideas. We are just as mistaken as a beginner in swimming who would attempt to learn several strokes before having mastered one well enough to keep afloat. A main text being of such importance, its choice involves responsibility. But how are we to know whether one book is superior to another until we have read both? And if we are confronted with this difficulty even when familiar with a subject, how much greater must be our task when we know nothing of it? These difficulties do not appear so formidable in practice. Failing other means, the best method of selecting a main text is by reputation. If we do not even know what book has the best reputation, we can easily find out by referring to so acknowledged an authority as the Encyclopedia Britannica, and consulting the bibliography in the article on the subject.