You know you have to read "between the lines" to get the most out of anything. I want to persuade you to do something equally important in the course of your reading. I want to persuade you to write between the lines. Unless you do, you are not likely to do the most efficient kind of reading.
I contend, quite bluntly, that marking up a book is not an act of mutilation but of love. You shouldn't mark up a book which isn't yours.
Librarians (or your friends) who lend you books expect you to keep them clean, and you should. If you decide that I am right about the usefulness of marking books, you will have to buy them. Most of the world's great books are available today, in reprint editions.
There are two ways in which one can own a book. The first is the property right you establish by paying for it, just as you pay for clothes and furniture. But this act of purchase is only the prelude to possession. Full ownership comes only when you have made it a part of yourself, and the best way to make yourself a part of it is by writing in it. An illustration may make the point clear. You buy a beefsteak and transfer it from the butcher's icebox to your own. But you do not own the beefsteak in the most important sense until you consume it and get it into your bloodstream. I am arguing that books, too, must be absorbed in your blood stream to do you any good.
Confusion about what it means to "own" a book leads people to a false reverence for paper, binding, and type -- a respect for the physical thing -- the craft of the printer rather than the genius of the author. They forget that it is possible for a man to acquire the idea, to possess the beauty, which a great book contains, without staking his claim by pasting his bookplate inside the cover. Having a fine library doesn't prove that its owner has a mind enriched by books; it proves nothing more than that he, his father, or his wife, was rich enough to buy them.
There are three kinds of book owners. The first has all the standard sets and best sellers -- unread, untouched. (This deluded individual owns woodpulp and ink, not books.) The second has a great many books -- a few of them read through, most of them dipped into, but all of them as clean and shiny as the day they were bought. (This person would probably like to make books his own, but is restrained by a false respect for their physical appearance.) The third has a few books or many -- every one of them dog-eared and dilapidated, shaken and loosened by continual use, marked and scribbled in from front to back. (This man owns books.)
Is it false respect, you may ask, to preserve intact and unblemished a beautifully printed book, an elegantly bound edition? Of course not. I'd no more scribble all over a first edition of 'Paradise Lost' than I'd give my baby a set of crayons and an original Rembrandt. I wouldn't mark up a painting or a statue. Its soul, so to speak, is inseparable from its body. And the beauty of a rare edition or of a richly manufactured volume is like that of a painting or a statue.
But the soul of a book "can" be separate from its body. A book is more like the score of a piece of music than it is like a painting. No great musician confuses a symphony with the printed sheets of music. Arturo Toscanini reveres Brahms, but Toscanini's score of the G minor Symphony is so thoroughly marked up that no one but the maestro himself can read it. The reason why a great conductor makes notations on his musical scores -- marks them up again and again each time he returns to study them--is the reason why you should mark your books. If your respect for magnificent binding or typography gets in the way, buy yourself a cheap edition and pay your respects to the author.
Why is marking up a book indispensable to reading? First, it keeps you awake. (And I don't mean merely conscious; I mean awake.) In the second place; reading, if it is active, is thinking, and thinking tends to express itself in words, spoken or written. The marked book is usually the thought-through book. Finally, writing helps you remember the thoughts you had, or the thoughts the author expressed. Let me develop these three points.
If reading is to accomplish anything more than passing time, it must be active. You can't let your eyes glide across the lines of a book and come up with an understanding of what you have read. Now an ordinary piece of light fiction, like, say, "Gone With the Wind," doesn't require the most active kind of reading. The books you read for pleasure can be read in a state of relaxation, and nothing is lost. But a great book, rich in ideas and beauty, a book that raises and tries to answer great fundamental questions, demands the most active reading of which you are capable. You don't absorb the ideas of John Dewey the way you absorb the crooning of Mr. Vallee. You have to reach for them. That you cannot do while you're asleep.
If, when you've finished reading a book, the pages are filled with your notes, you know that you read actively. The most famous "active" reader of great books I know is President Hutchins, of the University of Chicago. He also has the hardest schedule of business activities of any man I know. He invariably reads with a pencil, and sometimes, when he picks up a book and pencil in the evening, he finds himself, instead of making intelligent notes, drawing what he calls 'caviar factories' on the margins. When that happens, he puts the book down. He knows he's too tired to read, and he's just wasting time.
But, you may ask, why is writing necessary? Well, the physical act of writing, with your own hand, brings words and sentences more sharply before your mind and preserves them better in your memory. To set down your reaction to important words and sentences you have read, and the questions they have raised in your mind, is to preserve those reactions and sharpen those questions.
Even if you wrote on a scratch pad, and threw the paper away when you had finished writing, your grasp of the book would be surer. But you don't have to throw the paper away. The margins (top as bottom, and well as side), the end-papers, the very space between the lines, are all available. They aren't sacred. And, best of all, your marks and notes become an integral part of the book and stay there forever. You can pick up the book the following week or year, and there are all your points of agreement, disagreement, doubt, and inquiry. It's like resuming an interrupted conversation with the advantage of being able to pick up where you left off.
And that is exactly what reading a book should be: a conversation between you and the author. Presumably he knows more about the subject than you do; naturally, you'll have the proper humility as you approach him. But don't let anybody tell you that a reader is supposed to be solely on the receiving end. Understanding is a two-way operation; learning doesn't consist in being an empty receptacle. The learner has to question himself and question the teacher. He even has to argue with the teacher, once he understands what the teacher is saying. And marking a book is literally an expression of differences, or agreements of opinion, with the author.
There are all kinds of devices for marking a book intelligently and fruitfully. Here's the way I do it:
Underlining (or highlighting): of major points, of important or forceful statements.
Vertical lines at the margin: to emphasize a statement already underlined.
Star, asterisk, or other doo-dad at the margin: to be used sparingly, to emphasize the ten or twenty most important statements in the book. (You may want to fold the bottom comer of each page on which you use such marks. It won't hurt the sturdy paper on which most modern books are printed, and you will be able take the book off the shelf at any time and, by opening it at the folded-corner page, refresh your recollection of the book.)
Numbers in the margin: to indicate the sequence of points the author makes in developing a single argument.
Numbers of other pages in the margin: to indicate where else in the book the author made points relevant to the point marked; to tie up the ideas in a book, which, though they may be separated by many pages, belong together.
Circling or highlighting of key words or phrases.
Writing in the margin, or at the top or bottom of the page, for the sake of: recording questions (and perhaps answers) which a passage raised in your mind; reducing a complicated discussion to a simple statement; recording the sequence of major points right through the books. I use the end-papers at the back of the book to make a personal index of the author's points in the order of their appearance.
The front end-papers are to me the most important. Some people reserve them for a fancy bookplate. I reserve them for fancy thinking. After I have finished reading the book and making my personal index on the back end-papers, I turn to the front and try to outline the book, not page by page or point by point (I've already done that at the back), but as an integrated structure, with a basic unity and an order of parts. This outline is, to me, the measure of my understanding of the work.
If you're a die-hard anti-book-marker, you may object that the margins, the space between the lines, and the end-papers don't give you room enough. All right. How about using a scratch pad slightly smaller than the page-size of the book -- so that the edges of the sheets won't protrude? Make your index, outlines and even your notes on the pad, and then insert these sheets permanently inside the front and back covers of the book.
Or, you may say that this business of marking books is going to slow up your reading. It probably will. That's one of the reasons for doing it. Most of us have been taken in by the notion that speed of reading is a measure of our intelligence. There is no such thing as the right speed for intelligent reading. Some things should be read quickly and effortlessly and some should be read slowly and even laboriously. The sign of intelligence in reading is the ability to read different things differently according to their worth. In the case of good books, the point is not to see how many of them you can get through, but rather how many can get through you -- how many you can make your own. A few friends are better than a thousand acquaintances. If this be your aim, as it should be, you will not be impatient if it takes more time and effort to read a great book than it does a newspaper.
You may have one final objection to marking books. You can't lend them to your friends because nobody else can read them without being distracted by your notes. Furthermore, you won't want to lend them because a marked copy is kind of an intellectual diary, and lending it is almost like giving your mind away.
If your friend wishes to read your Plutarch's Lives, Shakespeare, or The Federalist Papers, tell him gently but firmly, to buy a copy. You will lend him your car or your coat -- but your books are as much a part of you as your head or your heart.