I've written before that you should take notes while reading advice articles. The more I've practiced this, the more I've come to believe that this is an essential learning tool (and one that I haven't been using properly for many years). This will probably seem obvious to those who already have a habit of taking notes from what they read, but for anyone else, please pay attention.
Note-taking as teaching
Taking notes, as I outlined almost a year ago, forces you to internalise the message you're absorbing, and synthesize it. There's no better way to learn something than to teach it, and taking notes is a private form of teaching.
Although in practice this will never happen, in theory, someone should be able to take your notes and figure out the gist of what the original author was trying to say. In order to explain that clearly and concisely, you need to carefully read, think about, understand, and internalise the book or article's message. You can't just skim through it while watching TV. You need to focus.
Note-taking as a quality filter
But notes do more than that. Note-taking also helps you quickly identify when the piece you're reading provides no value. If you're reading page after page and not writing anything down, it means that what you're reading is either empty, entertainment, or Art.
Some non-fiction books seem to ramble on forever without saying anything new. Malcolm Gladwell, for example, seems to have mastered the art of repeating the same point 200 times in a book while making you feel you're learning something. Blink has basically just one point: "Some of our thinking happens subconsciously and very quickly, and is surprisingly accurate". There, I just saved you ten hours of reading. This is still better than some abysmal non-fiction books which have zero point (and which shall remain nameless), but it's not great when compared to, say, Seven Habits, which is full of interesting, actionable ideas.
There's nothing wrong with reading books for entertainment (and Gladwell could be considered entertainment), but you should do so knowingly. As Paul Graham pointed out, the most insidious time-wasters look like they're productive work. If you identify books like Gladwell's as entertainment and accept them as such, fine. Just don't fool yourself into thinking you're learning something useful. Many fiction books are also obviously entertainment, and as a huge fan of fiction, I love and read them.
Finally, Art (primarily found in fiction rather than non-fiction) is a different kind of area altogether. I believe that the best books of mankind provide us with truly invaluable, deep insights into the meaning of life. Those are by definition so subtle and slippery that it is impossible to put them into short form. You have to live through them, personally or vicariously via a great writer's work.
For everything else, though, if there's nothing to write down, you're almost certainly not learning anything.
Notes as a repetition learning tool
One of the more awesome side-effects of taking notes is that it enables you to basically perform spaced repetition practice on yourself. It's well known that we learn through repetition. However, you can't keep re-reading a book every couple of weeks until it sinks in. That just takes too long.
I believe you need to read a book at least once to really understand the author's points. Derek Sivers' book notes are a great resource to get ideas for books to read, and to figure out whether you'll like a certain book or not, but you can't really learn properly from someone else's notes.
However, you can very well learn from your own notes.
This means that, for example, as you make your way through books like Cialdini's Influence, which can take a few weeks to absorb properly, you can refresh your memory regularly with your notes, and make sure that by the time you finish the said book, you haven't just read it. You've absorbed it. That's pretty much unachievable without notes.
Weeks after finishing a book, you can also spend 20 minutes or so re-reading your notes, and help settle the knowledge into your brain. The difference in terms of how much you actually retain is enormous.
If you're not taking notes, you're not learning
This leads me to a practical conclusion. The difference in learning between taking notes and not taking them feels, intuitively, like it's at least tenfold, maybe a hundredfold. If you don't take notes while reading a non-fiction, "teaching" book, you might as well not have bothered reading it.
Taking notes increases the time it takes to read that book, but it provides so much benefit that over the past few months, I've gotten into the habit of not reading any kind of non-fiction unless I have a way to take notes.
I warmly recommend that approach to you too. If you're not doing it yet, it's probably one of the most effective ways you can increase the rate at which you're learning and growing.
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