In your reading you must have in view some definite aim ---- some aim other that the wish to derive pleasure. I conceive that to give pleasure is the highest end of any work of art, because the pleasure procured from any art is tonic, and transform the life into which it enters. But the maximum of pleasure can only be obtained by regular effort, and regular effort implies the organization of that effort. Open-air walking is a glorious exercise; it is the walking itself which is glorious. Nevertheless, when setting out for walking exercise, the sane man generally has a subsidiary aim in view. He says to himself either that he will reach a given point, or that he will progress at a given speed for a given distance, or that he will remain on his feet for a given time. He organizes his effort, partly in order that he may combine some other advantage with the advantage of walking, but principally in order to be sure that the effort shall be an adequate effort. The same with reading. Your paramount aim in poring over literature is to enjoy, but you will not fully achieve that aim unless you have also a subsidiary aim which necessitates the measurement of your energy. Your subsidiary aim may be aesthetic, moral, political, religious, scientific, erudite; you may devote yourself to a man, a topic, an epoch, a nation, a branch of literature, an idea ---- you have the widest latitude in the choice of an objective; but a definite objective you must have.
Arnold Bennett: Literary Taste and How to Form It