But, really, it doesn’t matter how your [reading/note-taking] system works. It only matters that you have a system. Why? So that you can have a catalog of ideas that you can revisit. Parrish organizes his blank sheets by putting them into topic binders [...], and then sits down to look at his binders about once every two months. Over time, he finds himself remembering things and making connections he may not have otherwise, mastering these various subjects.
“Not only do you understand the book at a different level, but you're writing it down. It's tangible. Instead of rereading all these books, you can just pick up this binder. ‘Oh, this is great. I want to go back to this story. Maybe I missed something [here].’ You're connecting things across different domains or different situations. That's effectively how we improve our thinking.”