Take notes. In Albert Paine’s biography of Mark Twain, Paine wrote: “On the table by him, and on his bed, and on the billiard-room shelves, he kept the books he read most. All, or nearly all, had annotations—spontaneously uttered marginal notes, title prefatories, or comments. They were the books he read again and again, and it was seldom that he had nothing to say with each fresh reading.”
