Prof. Adler mentioned an illustration of beefsteak in order to prove

F: "Don’t ever mark in a book!" Thousands of teachers, librarians and parents have so advised. But Professor Mortimer Adler disagrees. He thinks so long as you own the book and needn’t preserve its physical appearance, marking it properly will grant you the ownership of the book in the true sense of the word and make it a part of yourself. Welcome to our show, Mr. Adler, so why do you think marking up a book is so essential?
M: Well, 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 first step to possession. (1) 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 bloodstream to do you any good.
F: I see. Then what if the book is a first edition of "Paradise Lost", a rare edition, or a richly manufactured volume?
M: I would say, 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’d buy myself a cheap edition and pay my respect to the author.
F: How does marking up a book help in reading?
M: (2) First, it keeps you awake, and I don’t mean merely conscious; I mean wide 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.
F: Can you explain, please?
M: Sure. 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. (3) 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. 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. 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.
F: (4) And that is exactly what reading a book should be: a conversation between you and the author.
M: Right. 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 your differences, or agreements of opinion, with the author.
F: How should we mark up a book in an intelligent way?
M: There are all kinds of devices for marking a book intelligently and fruitfully. Here’s the way I do it: (5) Underlining for major points, or for important or forceful statements. Vertical lines at the margin are used to emphasize a statement already underlined. Star, asterisk, or other doodads at the margin are used sparingly, to emphasize the ten or twenty most important statements in the book. Numbers in the margin are to indicate the sequence of points the author makes in developing a single argument. Number of other pages in the margin serves to indicate where else in the book the author made points relevant to the point marked. Circling of key words or phrases is recommendable. I write in the margin, or at the top or bottom of the page, for the sake of recording questions and perhaps answers, and of reducing a complicated discussion to a simple statement. I also 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, 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.
F: Great there. I really appreciate your way of reading. We usually read "between the lines" to get the most of anything, but here with Professor Mortimer Adler, we learned how to "write between the lines". Thank you, Mr. Adler.
M: Any time.