How to Take Smart Notes by Sönke Ahrens [Actionable Summary]

This is a comprehensive book summary of the book How to Take Smart Notes: One Simple Technique to Boost Writing, Learning and Thinking by Sönke Ahrens. Covering the key ideas and proposing practical ways for achieving what’s mentioned in the text. Written by book fanatic and online librarian Ivaylo Durmonski.

Printable summary: Download this summary to read offline.

The Book In Three Or More Sentences:

This book is a detailed dissertation of the famous Zettelkasten note-taking method – or slip-box in English. Created by Niklas Luhmann, a German sociologist, and philosopher, this extraordinary and non-linear way of taking notes is now one of the best-known techniques to put ideas on paper in order to remember things, craft academic papers faster, think deeply, and make connections between topics. If you’re a writer, or an aspiring academic, How to Take Smart Notes by Sönke Ahrens will introduce you to the leading methodology to take effective notes so you can later use them to generate new and better ideas on paper.

The Core Idea:

Good writing doesn’t necessarily mean slow writing. The effectiveness of your manuscript relies heavily on your note-taking skills. The gist of the book is to write down everything you find interesting and also to organize all the entries in one place. But just collecting ideas is not enough. True power comes when you start combining your findings. Sönke Ahrens wants to inspire us to start creating a “latticework of mental models”, not just to pursue remembering isolated facts.


  • Writing shouldn’t start with writing at all. It should start with creating a place where you gather ideas.
  • Avoid looking for the “ultimate” note-taking solution. Focus on the essentials.
  • Becoming a better writer will help you become a better idea generator.

5 Key Lessons from How to Take Smart Notes:

Lesson #1: Note-Taking is an Important Life Skill

Everybody writes.

But not everybody is a writer.

Note-taking might sound, seem even, unworthy of your time if you are not in academia. Yet, the simple habit of taking note of the things you found interesting in your day-to-day life can become the catalysts of your positive transformation – basically, it can save you from mediocrity.

Having a good note-taking system relieves you from the burden of remembering to-do items, scheduled appointments, but most importantly, helps you create a rich library of ideas and insights which you can later access on demand.

While the context of the importance of note-taking in the book is primarily aimed towards writers, and helping them create better material faster, I think that everybody can benefit from the approach mentioned in this short practical volume.

Once you establish a clear and easy-to-follow system of idea-collection, what follows is giving yourself permission to play with your findings so you can make new discoveries.

The technique that will be discussed in the following lessons aims to give you the flexibility to think about your ideas in more depth. To work with them. To combine them. And eventually, to come up with new interesting conclusions that can be of assistance in your daily life.

Sadly, this is not how most self-help books and even how our schools operate. Our institutions focus on memorizing fixed plans, facts, dates, and isolated ideas, so we can pass the exams.

But this narrow view and people’s inability to think beyond the learned material rarely leads to interesting insights. Actually, it’s turning students into planners – planning how to pass exams, not taking the time to actually understand the introduced ideas.

According to the author, truly groundbreaking discoveries happen when you have streams of ideas that you can later examine, think about, and mix.

If you’re a writer, the library of notes you collect will liberate you from the struggle of the empty piece of paper. You’ll never stall on your writing, and you’ll also think faster and better because you’ll have a strong foundation of ideas that you can rely on.

If you’re a student, or you’re simply working an office job, learning how to take notes will save you from your shortsightedness and give you the mental capacity to change your life for the better.

“When we look for patterns and think beyond the most obvious interpretation of a note, when we try to make sense of something, combine different ideas and develop lines of thought, we do exactly that: we build up a “latticework of mental models” instead of just “remembering isolated facts and try and bang ’em back.” Sönke Ahrens

Lesson #2: Understand Luhmann’s Secret Slip-Box Method

Instead of socializing, the 30 something German administrator, Niklas Luhmann, did the same thing daily after his 9 to 5 shift: He went home and immersed himself in books mainly on philosophy and sociology. And while reading, he noted the things he found interesting.

After years of collecting notes like most people do – writing in the margins of the book. Luhmann realized that this approach is not very effective.

So, he tried something else instead. He started writing down his thoughts and ideas on A6 cards. After the idea was added, he placed a number in the corner of every card and collect them all in a place called Zettelkasten (the slip-box).

But that was just the beginning.

Clearly, simply putting notes in one place would not lead to anything productive. As the author concludes, “Just amassing notes in one place would not lead to anything other than a mass of notes.”

That’s why he made small improvements in his process. He later developed new categories. He places index cards to differentiate different ideas and themes. He linked similar ideas together. And, he continued to add notes to his collection.

The thing he did not change was how new ideas were added on a card. Each card was a single idea and relevant ideas were linked together thanks to his numbering system.

For example, if he had 22 cards/ideas, 23 will be the number of the next one. If 23 was already used, and there was a discovery more closely related to what he wrote on card 22, he’ll number the new note 22a. This might seem like a limiting approach to some, but for Luhmann, it was a foundational element of his impressive workflow.

This simple technique earned him a name, and a title, in the field of sociology. And impressively, during his lifespan, he wrote 58 books and hundreds of articles. A feat that few academics could accomplish.

“He collected his notes in his slip-box in such a way that the collection became much more than the sum of its parts. His slip-box became his dialogue partner, main idea generator and productivity engine. It helped him to structure and develop his thoughts. And it was fun to work with – because it worked.” Sönke Ahrens

Lesson #3: Incorporate The Slip-Box Method In Your Life

If you want to write better books, articles, short guides. And if you want to write more of those, fast, don’t start with writing. Start with idea-collection. Start with creating your own slip-box.

A lot of people who produce written content are usually scared to death of the blank piece of paper. But their fear exists only because they missed an important step – they lack a pool of ideas.

If you have buckets of notes filled with insights, you’ll never agonize when you see the blinking cursors. You’ll simply open your notes and you’ll start arranging them.

How to start generating ideas?

Simple, create your own slip-box that will fuel your creativity and make you a human publishing press.

To understand how you can do this, let’s cover the basics of the slip-box method introduced in the book so you can implement it in your own life:


Professor Luhmann had two slip-boxes: The first was bibliographical, which he used to document notes related to the literature he consumed. The second one was his main slip-box. The place where the magic happened. Inside, he collected and generated ideas.

When he wrote notes that had to go inside his main slip-box, he always thought about his existing notes. And, he never directly copied quotes. He wrote the ideas by hand in his own words.

Here’s a short overview of the actual method:

The method:

  1. Make fleeting notes: Store your ideas immediately somewhere. The goal of the fleeting notes is to write down your thoughts whenever you have an epiphany. Even a napkin will do the job so don’t worry about getting a fancy notebook. Later, you’ll move these notes to a more permanent place.
  2. Make literature notes: This is your reference system. When you read articles, books, and other types of content, take note of the ideas you found interesting. Use your own words and strive to be short. Also, take the time to first understand the idea. Meaning that directly copying quotes should be avoided.
  3. Make permanent notes: All permanent notes go into your personal slip-box. Basically, your permanent notes collection is a combination of the notes from steps 1 and 2. You are simply transferring the insights into your vault of ideas having in mind what’s already inside. The main objective here is to think about how every new note will, and can be, related to what’s already existing. Think about combining ideas or supporting previous arguments.
  4. Adding a new note: You don’t just randomly place a new note in your slip-box. You think about how it relates to the other notes inside. Once you figure it out, you should place a new card behind a stack of similar ideas. Once this is done, you add a number. This number is linked to the previous note (22, or 22a, for example), or added to an index card (the next argument). You should be mindful during this stage. A new note should be either connected to a note that’s added to an index card, or, if it is not, you should then add a reference to the index card about this new note.
  5. Create index cards: A new card can be easily lost in the stack when added. To make sure you know what’s inside your slip-box so you can easily find it later, add index cards. These notes will contain keywords and sometimes the numbers of a couple of notes. For example, if the notes in the cards from 20 to 60 are covering two different concepts, you can place index cards in the middle of the stack to distinguish the different theories.

“After a while, you will have developed ideas far enough to decide on a topic to write about. Your topic is now based on what you have , not based on an unfounded idea about what the literature you are about to read might provide.” Sönke Ahrens

Lesson #4: Focus on The Essentials to Take Smart Notes

Traditional ballpoint pens, because of the lack of gravity, don’t work in space. That’s why NASA invested a lot of time and money to develop a pen that’s usable in space. The ink is pushed by compressed nitrogen and it allows you to write things down even if you’re floating around the endless space.

Sönke Ahrens mentions this story in the book because Russians also faced this problem but they solved it by using pencils.

The point the author is trying to make here is that it’s better to focus on the essentials when you’re taking notes. You don’t have to overcomplicate things and invest time and resources in sophisticated platforms with hundreds of options.

Sometimes, a lot of times actually, the simplest solution is the best solution.

It’s easy to fall into the trap of finding the best, ultimate note-taking application that will supposedly take notes for you. But this approach is a waste of time and does not contribute to the real purpose of taking notes – creating a comprehensive system of ideas.

Fancy writing and reading methods are constantly appearing online, promising to save you hundreds of hours. But in the end, they just make your workflow chaotic and hard to maintain.

If you want to take smart notes, you need only the following things – the essentials:

  1. Capture ideas: A place to capture your ideas as they appear. Throughout our days we’re constantly bombarded by different thoughts. The first thing you need to consider is a place to capture your fleeting ideas. You can use a physical notebook or an app. The goal here is not to take permanent notes. It’s simply to capture interesting concepts so you can later transcribe them into permanent notes.
  2. Create a reference system: This is exactly what the title suggests – have a dedicated place where you take notes from what you read. The author suggests having a dedicated place for this because this way you can easily document what you consume and avoid mixing these findings with your actual notes. In the book, the following program is recommended: Zotero.
  3. Get a slip-box: Your slip-box is the place where you put permanent notes and where you move your notes from step 1. You can either use the old-fashioned pen and paper accompanied by a real wooden box with cards. Or, you can find a similar online solution. The program that’s recommended in the book is the following one: Daniel Lüdecke’s Zettelkasten.
  4. Editor: The fourth step is referred to as a place where you can play with your ideas. Mix them together so you can produce something on your own. Of course, you can either use an online editor or simply use your physical notebook.

“Creative people are better at recognizing relationships, making associations and connections and seeing things in an original way—seeing things that others cannot see.” Nancy Andreasen

Lesson #5: Generate New Ideas Using Your Slip-Box

Okay, say that you have your notes ready and adequately organized inside a physical box. Or, let’s say you decide to use software for this job. What do you do from here?

If you did your job properly, this means that you have an excess of possible ideas sitting in front of you. Now you simply have to make connections so you can further develop your findings. Or in other words, you have to start writing.

Here is a 6-step process that will show you how to become a better writer (idea-producer):

  1. Focus on one task: Our productivity suffers when we constantly switch between tasks. Media outlets are contributing to our degenerating attention span. While in the 70s the average soundbite during elections was around 40 seconds, now this same form of media is averaging to about 8 seconds. This means? We need to focus on one task at a time because our attention span is sufficiently lower than what it used to be years ago. Cut distractions when you’re writing to actually produce writing.
  2. Avoid multitasking: The best way to deal with information overload is not to look at several things at once. Separate tasks and do one thing at a time. People who claim to be good at multitasking are usually wrong in their assessments.
  3. Separate writing from editing: While proofreading is part of the writing process, it should be done only when the writing part is finished. Or in other words, don’t edit while you write. These two tasks require completely different parts of the brain. When you try to edit while you write it’s like you’re constantly switching between your left and right hemisphere. This not only slows you down but also disturbs your creativity.
  4. Don’t be a planner, be an expert: You can spend weeks planning but if you don’t move forward your plan will be just a waste of time. Great writers achieve virtuosity by doing the work. Rules and plans might prepare you for possible setbacks but real experience comes from doing. So, regardless of what you’re writing, or even doing, start practicing it as soon as possible so you can get feedback and make adjustments.
  5. Close tasks by writing them down: We have limited space in our short-term memory. Studies mentioned in the book state that, “we can hold a maximum of seven things in our head at the same time, plus/minus two.” This means that if our brains are preoccupied with thoughts about things we must do, we won’t be able to focus on our writings. To “close” tasks, you can simply write them down. By noting something you must do, our brain can rest assured that this will be done. Get things out of your short-term memory so you can focus on what’s important now.
  6. Reduce decisions: Our mental capacity is slowly depleting during our day. The more decisions we have to make, the faster we’ll exhaust our resources. The simplest solution here is to design your environment by making it less willpower demanding. This means removing distracting objects (phone, TV, arranging your desk the night before) and reducing decisions. Famous people like Barack Obama and Bill Gates wear the same clothes for a simple reason: they have one less decision to make which gives them more willpower to focus on the important things.

“Letting thoughts linger without focusing on them gives our brains the opportunity to deal with problems in a different, often surprisingly productive way. While we have a walk or a shower or clean the house, the brain cannot help but play around with the last unsolved problem it came across.” Sönke Ahrens

Actionable Notes:

  • Create a slip-box: The power of the slip-box is twofold: First, it allows you to create a library of notes and ideas that will later fuel your writings. You’ll never get stuck because you’ll have a vault full of ideas and rough drafts. Secondly, forcing yourself to write the actual note allows you to think deeply about the topic. We tend to think that we understand something just by reading it but this is usually not the case. True understanding comes when you take the opportunity to write what you read in your own words.
  • Find what didn’t work: Our culture is over-obsessing about success and about things that are working. Sadly, we never spend time thinking about why certain projects or companies fail. Understanding failure and what causes failure, in many cases, can be much more valuable than exposing yourself only to successful stories. People try to hide their shortcomings and wrong attempts because they think these things will discredit them. But failed attempts are more interesting and can be a lot more valuable than what worked. Taking the time to find what didn’t work in a project will strengthen your knowledge, and most importantly, help you find better ways to make things work.
  • Tools are just tools: Having the right tools to take notes is an important step but it can also become a problem. Since there are numerous apps and note-taking techniques available online, it’s easy to get lost in the chaotic search for the “best” tool. As the author writes in the book, “tools are only as good as your ability to work with them.” For example, even if you get the best guitar on the market this doesn’t mean that you’ll play like Jimi Hendrix. The slip-box method is simply a tool to take notes. Don’t romanticize about getting the fanciest software or the prettiest cards, focus on the outcome you want to get from your note-taking practice. Do you want to become a better researcher or you simply want to remember more things? The outcome you want to achieve will help you tailor the process for your needs, not the other way around.
  • Think inside your box: Once you have a pile of ideas written down, it’s obviously time to make some connections between them. Usually, researchers will think that more notes are needed to produce some sort of text but that’s usually a false belief. We tend to spend more time scrapping for new ideas instead of using what’s already ready and available. A good habit is to take a moment to recognize the hidden ideas in what you already noted. Your ability to identify the gist, tie simple ideas together, and turn them into better solutions will make you a better thinker and ultimately, a better writer. All you need to do is practice.
  • Make smart connections: Tying different ideas together is the secret sauce that made Niklas Luhmann one of the most respected sociologists of our time. He wasn’t just collecting notes in isolation, he was actively looking for ways to connect them. This way, he was able to bridge different insights and develop never-discussed before topics. This should be your main goal. To build a latticework of ideas and mental models instead of just collecting and remembering facts in isolation that serve no purpose at all.

Commentary and My Personal Takeaway

Taking notes is one of the best ways to grow intellectually. And while How to Take Smart Notes is targeting mainly students, academics, and writers, the benefits of the system described in this short how-to book are apparent for everyone.

The goal of Sönke Ahrens in this book is to relieve our brains from the burden of remembering stuff and keeping track of everything. When you outsource your findings to a simple system where everything is categorized and noted, you won’t have to constantly dig deep inside your brain to find facts. You’ll allow yourself to forget ideas which, paradoxically, will reinforce your ability to understand these findings better.

How to Take Smart Notes is a detailed guide that promotes the Zettelkasten note-taking method created by Niklas Luhmann. If you’re unfamiliar with the slip-box method by Luhmann, I highly recommend checking online for more information and also even getting the book. Ahrens describes in a really simple matter how to adopt this profound note-taking approach and implement it in your life.

If you already know the Luhmann’s secret, this book probably won’t tell you anything new. It will be only worth checking if you’re still not quite satisfied with your note-taking approach.

Key takeaway:

Simple ideas when mixed together can lead to groundbreaking discoveries. That’s actually how new systems and emerging markets are born – by finding connections between simple ideas. Your ability to find relationships between basic components will make you an elite pioneer.

Notable Quotes:

“There is no need to build a complex system and there is no need to reorganise everything you already have. You can start working and developing ideas immediately by taking smart notes.” Sönke Ahrens

“Instead of having different storage for different ideas, everything goes into the same slip-box and is standardised into the same format.” Sönke Ahrens

“Most often, innovation is not the result of a sudden moment of realization, anyway, but incremental steps toward improvement. Even groundbreaking paradigm shifts are most often the consequence of many small moves in the right direction instead of one big idea.” Sönke Ahrens

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