Reading with an Underline Is a Trap

Through elementary, middle, and high school, we learn to read by highlighting and underlining. Reading for exams in particular cements the habit. Everyone has the experience of busily underlining their way through a reading-comprehension section. Then the exams end, and we no longer have any chance to improve our reading.

A good reading strategy is to internalize the content and make it your own. So when you read a book, you shouldn't stop at highlighting or underlining. A summary in your own words is fine, but far better is to internalize the material and rewrite it to fit your own situation and context. That is why we should write reading notes or reading cards. It is the same as writing a literature note (reference note) in the Zettelkasten method.

Highlighting and underlining do not internalize the content of a text. Worse, they can give you the feeling that you understood it perfectly.¹ Yet highlights and underlines are forgotten as time passes. Many of us have already experienced this.

Nor can they serve as reference material for developing an idea. That is because you neither revised the content to be close to your own thinking nor gathered it in one place. So when you later try to consult the material, highlights and underlines don't help. You vaguely remember that a related idea appeared somewhere, but it's hard to tell which book it was in.