How to stop forgetting what you read

My approach to the four levels of reading and note-taking


A few months ago, I realized I have a problem. I read a decent amount of books. But when people asked me ‘so what’s the book about’ I could only recount random bits, and usually didn’t recall all its main arguments. Worse even, a few months down the road, I had forgotten most of a book’s content. Damn you, human memory!

I came across Julie Zhuo’s awesome article, Always Be Learning, where she describes what she learned coming from a similar situation:

The value from reading doesn’t come from quantity. I used to think it was way better to read twenty books than two. Now, I think what matters most is how much you retain. It’s a shame how many thousands of books I’ve completed that I can’t really tell you very much about.

I started looking for more effective ways of reading. My goal was to learn more and forget less.

There were two main ideas: the four levels of reading, and the importance of taking notes. After some experimenting and tweaking, I came up with a ‘reading system’ based on both ideas. It’s been working well for me, so I want to share it with you — here’s what I learned.


1. Understand the four levels of reading

Mortimer Adler wrote a book on how to read — it’s appropriately titled ‘How to Read a Book’. You can find a great summary of the main ideas by Shane Parrish here.

He describes reading as an active skill and not just the passive activity of turning pages. There are four levels of reading:

  1. Elementary reading. The kind of reading you learn in elementary school. If your goal is just information or entertainment, elementary reading is enough. After this level you can answer the question, “What does the sentence say?”
  2. Inspectional reading or skimming. You check out the title of the book, table of contents, preface, etc.. I also find Amazon reviews helpful at this stage because many readers summarize the key points of a book in their reviews. After this level you can answer the questions, “What’s this book about? What’s the structure of the book? Does this book deserve my time and attention?”
  3. Analytical reading. You read the whole book thoroughly, and engage your mind to deeply understand what the author says. This takes time. After analytical reading you can summarize the whole book in a few short sentences (as is you were teaching someone about it), name its major arguments in their order and relation, and define the problem the author is trying to solve.
  4. Syntopical reading. The highest level goes beyond a single book. You read more authors who write about the same topic, and compare and contrast their arguments. It’s the most demanding level of reading. The aim of this level is to not only understand one book, but to develop fluency in the subject matter itself. In the end, you will have formed an informed opinion based on multiple perspectives — you will truly understand the topic you set out to learn about.

The four types of reading are called levels because you can’t move to a higher level if you don’t have a good understanding of the previous level.


To put the theory to test, I applied it to a topic I’d wanted to learn more about for a while: emotional intelligence. I set out to gain basic understanding and find mental models I can apply to make decisions and solve problems.

My reading list so far is an example of how you can approach one topic from many different angles:

How did I find these books? Most books were recommendations from people I trust — co-workers, friends, and experts in their fields. Curated reading lists like ‘Books for Product Managers’ by Ken Norton are great for this. You can google [topic of your choice] + ‘reading list’ and there’s a good chance you will find amazing books.

I put these recommendations into a list and usually double-check on Amazon by reading the reviews. Then it’s all about prioritizing which book comes next.


2. Take good notes of what you read

To be able to compare and contrast books, articles, and talks among themselves — syntopical reading — I take notes of what I read. While reading, I underline key passages from the main arguments the author is making.

My copy of ‘Getting past No’ by William Ury

Some parts of a book contain lots of highlights for me (like the one above), while other pages will be blank.

After I finish a book, I let it sleep for a while. I wait at least a few days until I go through it again. This time, I re-read the underlined passages and transcribe them into a document where I keep all my notes.

My notes are not organized by authors or books, but by topics and skills I can improve. In the example of emotional intelligence, here’s what it looks like today:

I use Google Docs for the actual notes and an ever-evolving Medium post to track the sources. The number you see on the right is the page number in the Google doc (I currently have 214 pages of notes in total). There are tons of other note-taking tools like Evernote out there — pick the one which works best for you.

Let’s come back to our example. Within my wider system of notes, ‘emotional intelligence’ is one of several subjects. You can see below how it fits in the bigger picture. I’m a product manager which explains the choice of topics ✌:

How I structure my notes (built with D3.js)

Some books I read open up a whole new topic and many ideas and arguments around it. One such book is ‘Emotional agility’ which introduces the concept of the same name and provides tons of actionable ideas to try. Other books like ‘Crucial conversations’ add insights to many different, superficially unrelated areas: emotional self-awareness, persuasion, negotiation techniques, and effective listening.

The whole structure evolves continuously. That’s a good thing, as I’m not trying to map all the knowledge in the world. What I want is to make connections between ideas and arguments I pick up in different places. If you were to build your own version, it would look completely different.

“Scientists generally agree that no theory is 100 percent correct. Thus, the real test of knowledge is not truth, but utility.” Yuval Noah Harari

I usually have my notes document open in a browser tab. When someone asks me a question, I often find parts of an answer somewhere in my notes. I take every chance I get to teach what I learned — giving presentations, writing a blog post about a topic, etc. And of course, whenever I come across an interesting idea, I add it to my notes to reference it later.


It’s now been a few months since I started using the four levels of reading and taking notes. I’ve found the additional effort to be well worth it. I can reference back to an increasingly large collection of knowledge from the smartest people. It helps me save time and improve my approach whenever I explain or present an idea I didn’t entirely come up with myself — which is most of the time.

The patterns which emerge from connecting different authors and disciplines are the first principles and mental models I apply every day to make better decisions and solve problems.

“Men [and women] who have made these discoveries before us are not our masters, but our guides.” Seneca

If you learned something from this post (or enjoyed reading this far), I’d appreciate if you “Clap” below and follow me for future stories


PS: I started to use this approach to reading some months ago, which means it’s too early for me to mention re-reading books in this post. If you’ve read a good book some years ago, there’s a good chance your mental models and thus perception of reality have changed a lot. It makes sense to re-read these books from front to cover — you will effectively be reading a different book and learn many new things.