Yeah I've found that many people have a weird hangup about this. I guess it's because of how they learned to study in school. You're "supposed to" finish the book.
In my mind, the point of reading is learning/retention/permanent change, not "completionism" in finishing the book. I just get a bunch of books from the library, and read the PARTS of the ones I feel like reading, that I feel have some relevance. I get 5 books for every one I finish, and I don't feel bad about it.
Often when I get to a "bad part" (and most books are filled with bad parts), I just read the first sentence of every paragraph, and nothing is lost. Paradoxically, you may get more retention that way! The bad parts have low information density.
But there has to be some retention, and I have a couple tactics for that:
- I take notes on every book I read. Key point: it's not a lot of notes. It's not page-by-page notes, and I don't do it while I read. It can be 4 sentences for some entire books. If you can't remember the notes you want to write after 24 hours, then the book might not be that good.
- I take notes in a wiki and use hyperlinks. If what you read doesn't cause you to think of some other book you read, or something someone said, then you probably didn't learn anything. Everything is related, and different authors say the same thing in different ways. If you're not recognizing that, then you're probably reading the material without understanding it.
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Related:
http://www.paulgraham.com/know.html
What use is it to read all these books if I remember so little from them?