Reading with a Highlighter Is a Trap

Through elementary, middle, and high school, we learn to read with highlights and underlines. Reading for exams in particular cements the habit. Everyone has had the experience of reading a passage on the Korean language section of the exam, busily underlining as they go. And once the entrance exam is over, we lose any chance to improve our reading skills.

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. This is the same as writing a literature note (reference note) in the Zettelkasten method.

Highlights and underlines do not internalize the content. Worse, they can give you the feeling that you understood it perfectly.¹ And yet you forget what you highlighted and underlined as time passes. Many of us have already experienced this.

Nor can they serve as reference material for developing an idea. You haven't revised the content to fit your own thinking, and you haven't gathered it in one place. So highlights and underlines are hard to use when you later want to consult the source. You vaguely remember something, but it's hard to tell which book the related idea came from.