Book: How to Take Smart Notes


How to Take Smart Notes is a cross between a manual and a self-help book by Sonke Ahrens. Do you want to remember more from what you read? This book might help you with that. It will give you advice and methods to systematically record and connect ideas.

The author explores the methodology of Niklas Luhmann, a renown sociologist. Luhmann was prolific and published a vast amount of articles and books during his carrier. Studying how he worked might teach us useful skills. Luhmann described that the source of his thinking and success came from the help of his Zettlekasten. Zettlekasten is the german word for a slip-box. The secret of his productivity is index cards!

When I was a student, I waited for the last moment to write my final year dissertation. I started from a blank page with a few ideas in my mind. It was hard to decide on what to write about and focus on. I didn’t do a good job. What could I have done differently? This book gave me an answer that I wish I had at the time.

The answer is simple: take notes of what you read, listen or watch. Following your interests will lead you to discover what you want to write about and avoid the blank page. Instead of forcing yourself to find ideas from thin air, your job will be to connect your notes and expand their content. You will not write from scratch because you will have all these notes to help you.

“Writing is not what follows research, learning or studying, it is the medium of all this work.”

Why should you follow the Zettlekasten methodology or a least take notes in your way? First, you will be able to learn and retain better what you learnt. Second, you will be able to connect ideas and create new thoughts.

Why should you take notes

Remember more of what you read and think

Writing things down will help you learn and spot area that is not clear in your mind. Writing will also enable you to communicate your ideas and share them with the world.

“Writing is, without dispute, the best facilitator for thinking, reading, learning, understanding and generating ideas we have.”

When your computer has not enough place in RAM, it commits data to the hard drive. Writing does the same for your brain. It free up precious brain RAM.

Writing is a thinking tool

By feeding your slip-box with many notes, you will, at some point, create a toolbox for finding new ideas and inspiration.

“Most people still think about thinking as a purely internal process, and believe that the only function of the pen is to put finished thoughts on paper. Richard Feynman once had a visitor in his office, a historian who wanted to interview him. When he spotted Feynman’s notebooks, he said how delighted he was to see such “wonderful records of Feynman’s thinking.” “No, no!” Feynman protested. “They aren’t a record of my thinking process. They are my thinking process. I did the work on the paper.”

“Taking permanent notes of our own thoughts is a form of self-testing as well: do they still make sense in writing? Are we even able to get the thought on paper? Do we have the references, facts and supporting sources at hand? And at the same time, writing it is the best way to get our thoughts in order. Writing here, too, is not copying, but translating (from one context and one medium into another). No written piece is ever a copy of thought in our mind.”

The case for pen and paper

It’s a matter of preference, but there seem to be some advantages from writing with a pen. Handwriting is slow and requires much more effort. In a way, this is what is so good about it. Handwriting force you to be succinct and to translate things in your own words.

“Handwriting makes pure copying impossible, but instead facilitates the translation of what is said (or written) into one’s own words. The students who typed into their laptops were much quicker, which enabled them to copy the lecture more closely but circumvented actual understanding. They focused on completeness. Verbatim notes can be taken with almost no thinking, as if the words are taking a short cut from the ear to the hand, bypassing the brain.”

How do I start?

Ready to make your Zettlekasten!

First, pick up your tools. It depends if you are going digital or analogue or why not both. Choosing the tool, that looks and feel the right way to you is, in my opinion, very important. For me having a great pen and paper help me do the work.


  • A Zettlekasten app. See this list. The most popular are Roam and Obsidian.
  • A reference manager app. See this list. I guess this applies if you are writing an academic paper or book. This is the place where you will store citations and references to other people work that you mention in your writing. There are a few software that will help you with that.


  • A nice pen.
  • A stack of nice index cards.
  • An index card box.
    • I haven’t invested in one yet. I use an elastic band to hold them together.

How to organise your notes?

A Zettlekasten is like a social graph for notes. Your notes don’t follow a particular hierarchy as they would if they were written in a notebook. Your notes are connected and belong to cliques within a graph.

A notebook won’t work! The idea behind the Zettlekasten is independent notes organised in a non-chronological way. What about using folders? Folders and sub-folders are not a great way to store notes because they impose a rigid organisation. A note on Entropy belongs to the maths, computing or physics folder? With folders, it is impossible to find connections between discipline. What about tags? Tags are a bit like a folder. However a notes can have multiple tags: the note on Entropy can have the maths, computing and physics tags. Tags are good, but there is something even better: links.

Hold on, is a Zettlekasten a Wiki? Yes and no. A Zettlekasten is not about creating an encyclopaedia. It’s about creating a network of notes and following a strict discipline. Let’s explore how it works.

The Zettlekasten algorithm

  1. Create temporary notes.
    • Always carry something to take notes with so you can capture any passing thoughts.
    • When reading or listening to a podcast, for example, write down any interesting facts in your own words. Keep these notes along with the references in your reference manager.
    • Be parsimonious. Think about how those temporary notes are relevant to your interests.
  2. At a later time, create permanent notes from the material gathered at step 1. Temporary notes are drafts for the permanent notes.
    • Develop thoughts from the temporary notes. Find how they relate to existing notes in your slip-box.
    • Precise the references you used. Where did your thought come from?
    • Give you permanent note an identifier (could be a series of letter and numbers for example). A Zettlekasten app will generate one for you.
    • Reference the related notes by using the identifiers. Explain why you are linking the notes. How are they related? How does this new thought compare to another? Find possible contradictions, paradoxes or oppositions with existing notes.
  3. Store your new notes.

What makes a good note?

A good note focuses on one and only one idea.

A good note has a good title: the title should convey the idea or the thought.

A good note should have references. Where did the idea or thought come from? What is the supporting material?

A good note should share at least a link with another one. The existence of the link should be explained.

“The notes are no longer reminders of thoughts or ideas, but contain the actual thought or idea in written form. This is a crucial difference.”

The Zettlekasten way of life

The Zettlekasten is a forcing-function that will make you read a book or consume media with more focus. You will soon be addicted by the urge to feed your Zettlekasten. The benefits that come from it will compound with time.

“Studies on highly successful people have proven again and again that success is not the result of strong willpower and the ability to overcome resistance, but rather the result of smart working environments that avoid resistance in the first place (cf. Neal et al. 2012; Painter et al. 2002; Hearn et al. 1998).”

If you are not already taking notes of what you read, listen or watch, it might be a daunting task to try. You want it a habit. I find it very hard to take notes while reading. How can you take notes when reading in public transport? Do you carry the book and then a pen and paper with you? Do you read on a Kindle?


“An idea kept private is as good as one you never had. And a fact on one can reproduce is no fact at all. Making something public always means to write it down so it can be read. There is no such thing as a history of unwritten ideas.”

“The ability to generate new ideas has more to do with breaking with old habits of thinking than with coming up with as many ideas as possible. For obvious reasons, I do not recommend “thinking outside the box”. On the contrary, we can turn the slip-box into a tool for breaking out of our own thinking habits.”

“The biggest threat to creativity and scientific progress is therefore the opposite: a lack of structure and restrictions. Without structure, we cannot differentiate, compare or experiment with ideas. Without restrictions, we would never be forced to make the decision on what is worth pursuing and what is not.”

More about Zettelkasten on the Internet