What Mortimer Adler is trying to convey in “How to Mark a Book” is that reading means consuming, and marking up a book doesn’t mean that you are vandalizing it. It means that you are showing the book love, and that you are giving the author your respect. He advises that you should “write between the lines”, as that is equally important as reading between the lines. He believes that the practice of writing between the lines helps you to get the most out of the book you are reading. Adler goes on to state that marking up a book is imperative to your reading. He expresses that it prompts you to engage in a more active form of reading; a form in which you are kept wide awake, and that this form of reading also helps you to absorb the full meaning
