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. Supporting Members get full access.

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

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