The choice is relatively bad when, spreading over a number of books, it pursues no order, and thus results in a muddle of faint impressions each blurring the rest.  Books must be allowed to help one another; they must be skilfully called in to each other’s aid.  And that this may be accomplished some guiding principle is necessary.  “And what,” you demand, “should that guiding principle be?” How do I know?  Nobody, fortunately, can make your principles for you.  You have to make them for yourself.  But I will venture upon this general observation:  that in the mental world what counts is not numbers but co-ordination.  As regards facts and ideas, the great mistake made by the average well-intentioned reader is that he is content with the names of things instead of occupying himself with the causes of things.  He seeks answers to the question What? instead of to the question Why?  He studies history, and never guesses that all history is caused by the facts of geography.  He is a botanical expert, and can take you to where the Sibthorpia europaea grows, and never troubles to wonder what the earth would be without its cloak of plants.  He wanders forth of starlit evenings and will name you with unction all the constellations from Andromeda to the Scorpion; but if you ask him why Venus can never be seen at midnight, he will tell you that he has not bothered with the scientific details.  He has not learned that names are nothing, and the satisfaction of the lust of the eye a trifle compared to the imaginative vision of which scientific “details” are the indispensable basis.

Most reading, I am convinced, is unphilosophical; that is to say, it lacks the element which more than anything else quickens the poetry of life.  Unless and until a man has formed a scheme of knowledge, be it a mere skeleton, his reading must necessarily be unphilosophical.  He must have attained to some notion of the inter-relations of the various branches of knowledge before he can properly comprehend the branch in which he specialises.  If he has not drawn an outline map upon which he can fill in whatever knowledge comes to him, as it comes, and on which he can trace the affinity of every part with every other part, he is assuredly frittering away a large percentage of his efforts.  There are certain philosophical works which, once they are mastered, seem to have performed an operation for cataract, so that he who was blind, having read them, henceforward sees cause and effect working in and out everywhere.  To use another figure, they leave stamped on the brain a chart of the entire province of knowledge.