Sönke Ahrens is an independent researcher and coach. He is best known as the author of How to Take Smart Notes, a popular book on the zettelkasten method of note-taking. In this conversation, we discuss the role of notes in thinking and learning, with a focus on zettelkasten-inspired note-taking.

Show notes

Show notes include Amazon affiliate links. We get a small commission for purchases made through these links.

If you're enjoying the show, please rate or review us in Apple's podcast directory:

This episode's transcript was produced by an AI. If you notice any errors, please get in touch.


Jorge: Sönke, welcome to the show.

Sönke: Thank your for having me.

Jorge: I’m very excited to have you. Your book has been very influential to me. It’s a reference point for people who are working in taking notes who are interested in taking notes. But some folks who are listening in might not be familiar with you and your work. How do you introduce yourself?

About Sönke

Sönke: My background is in philosophy of education. I am now an independent researcher. I am interested in interdisciplinary questions. For example — maybe most relevant for our topic today — in what makes people change their mind. And what makes it easier to change one’s mind? Yeah! And I’m the author of How to Take Smart Notes, the reason you invited me today.

Jorge: I think that the title of that book is very descriptive of what the book is about. But you prescribe in the book a very particular approach to note-taking. When you say ‘smart notes,’ it refers to a very particular approach and I was hoping that you would describe that for listeners.


Sönke: I’m excited about the conversation we have because you’re coming from the digital side to note taking and the approach I described in the book is coming from the analog side, and it’s based on an idea of an enormously prolific social science author, Niklas Luhmann, a German scholar.

He is in some parts of the world extremely famous and in some parts completely unknown. Mostly known for his work on systems theory, especially in the social sciences. But with contributions in almost any array you can think of. So he wrote about arts and economy, politics, you name it.

And little attention was paid to his practical side — to the practical side of his work. And just to give you an idea about how prolific he was, he wrote about 60 books in 30 years. Hundreds of articles, translations not included! And they are not repetitive. They have a similar structure because he has a very developed terminology in systems.

But it’s a very dense way of writing. So, obviously, as a writer myself, I was interested in his approach to writing. And he wrote only two pieces and gave one interview where he went a little bit into details. Nowadays, there is a research project at his old university, Bielefeld, that is working on what is called his zettelkasten.

So that’s translated into slip box and contains out of all together roughtly 70,000 individual notes connected in what might seem to us like a hypertext structure. But it’s tightly connected to the analog system he used. So, it’s not directly translatable into the digital. And a lot of discussions nowadays in the personal knowledge community is about how to translate the analog system into the digital.

But there are a few core ideas about his system that I think can be easily translated and one is the idea of what we might today call atomic notes. So, you have one idea per note and you have a loose structure. His notes were connected by standing order, so they were not hierarchical sorted by topic, but he would just write one note, add another note that refers to the note before.

And by his system, he branches out ideas, and you get these branches of note sequences that you also recognize in his articles. So it’s a very bottom-up process of developing ideas with a strong emphasis on his own thinking.

And that is one of the main differences to typical note taking systems taught in school and university where the emphasis is on collecting ideas of other people and storing them in a particular way. The emphasis here is really on developing your own ideas — of course, informed by the ideas of others. But the decision where to put a new idea is really by: does it expand on something I’m already working on? And maybe we can go a little bit more into detail. But when you want to picture the system, a lot of draws with a lot of index card sized paper notes, only written one sided so he doesn’t have to take them out. And also written on thin paper so it doesn’t fill the whole room up with 70,000 notes, which of course, takes up a lot of space.

Jorge: I was going to ask you about that because you had hinted at the fact that it was analog. But I think that in this day where so many of us use digital devices all the time, I think it’s almost hard to visualize such a thing, right? And there’s a website where Luhmann’s index cards are scanned and you can peruse them. And I don’t speak German; I can’t read German. So I can’t read the actual content, but just looking at these things, it’s astonishing to me that he would keep his thoughts in a physical… in this kind of physical memory, which I envisioned as being quite large, because 70,000 slips of paper is not a small number.

Sönke: Yeah, Yeah. There was actually a discussion between his children because in the inheritance was split up to his son who inherited the house with the furniture and his daughter who inherited the intellectual body of work. And his son argued, “well, the zettelkasten is obviously a piece of furniture. A huge one!” And the daughter of course argued, “well, no. That’s pretty much the center of his intellectual work.” But, yeah. It is huge and I can highly recommend even if you don’t speak German, to look up the digitalized version, because you get an impression of how it looks. And you also get an impression just by the way the notes are written and how he connected them by handwritten links how the process might have looked like.

Jorge: The impression that I get — and again, I’ve only perused the scans — but also from reading about his approach, the impression that I get is that he came up with a very idiosyncratic addressing scheme so that each note could have a unique identifier, that could be used as a reference from other notes, right?

Categories and identifiers

Sönke: Right. Well, basically in the beginning, he started with rough categories but they are not really important. To understand the signifiers the easiest is to think of the first note as the note, Number 1. And the second note, Number 2, and so on. But if you want to add a comment to note Number 1 while already note Number 2 is there, you would just put it in between and then name it 1A. And by alternating numbers and alphabetic letters slash another comma in between you can practically indefinitely branch out new strands so that the original note sequence might later be interrupted by hundreds of notes, but you will still be able to reconstruct what the original note sequence was before it was interrupted.

So, it’s not quite like a hypertext because the emphasis is on these note sequences. You still see the physical sequence of the notes and at the same time, by having a unique number for each of these notes, you’re able to reference them. And that is maybe best described as a loose structure, somewhere in between a linear text and hypertext, but with an emphasis on these note sequences. And that’s also the main difference to a personal wiki, because it’s not just a collection. It’s a densely connected network where notes comment on other notes, expand on other notes and you don’t just collect facts or ideas but you look for the connections. And the connections are where the magic happens.

Jorge: I want to talk a bit more about the connections because it does feel like that’s one of the things that makes this approach so different from other approaches. The impression that I’m getting and hearing you talk about it is that in something like a hypertext or, use the image of a wiki, which I expect most people will be familiar with, the connections between ideas can happen in a very bottom-up way, right? Like, where if I’m writing a sentence and I want to create another note that focuses on the word ‘sentence,’ I just make a link then and there, and it’s kind of this arbitrary bottom-up connection that emerges. But what I’m hearing here is that in Luhmann’s original zettlekasten, the connections are more sequential.

Sönke: Yeah.

Jorge: It’s almost like a multiverse text in some way that you’re… it’s like you’re starting down a linear path, but it can branch off, right?

Connecting concepts, not just words

Sönke: Exactly. Yeah. And I think the the mindset people often have when they link, like, to a particular word, it’s a focus on the word itself and not on the concept and the idea behind the word. Luhmann also had an index to quickly find his way around the zettlekasten. But he also had like ‘hub’ notes where he points to different aspects of a particular topic.

And I think the difference between concepts and words are extremely important because you have to understand what you’re linking to. You’re not just linking to something that happens to have the same word, but you link to something that is actually on a content level relevant for the idea you’re developing. And that note you’re linking to might not even have the same word in it. It might be discussed with another term or another concept or another word. So it’s a system that nudges you constantly to reflect on what you’re actually talking/writing about, and any connection that makes sense has to be a connection that is well understood.

I myself try to link in a way that the link is embedded in some kind of sentence that describes the connection, so I don’t collect random links which quickly become overwhelming after a while. But that I give myself an account on why do I link to that particular note: how is that helpful for the idea I’m trying to express, the thought I’m trying to develop? And that gets you quicker into deep work instead of the shallow work where you more or less just organize the ideas.

Jorge: Yeah. This is a subject I was hoping we would get into. I call this distinction the difference between doing the work and then doing what I call meta-work. Like, working on the thing that enables the work. And one impression that I’ve had about Luhmann’s approach is that because it was analog, it required a lot of kind of housekeeping — maybe literally, in his case, because it is a big thing in his house! But interestingly, one of the things that’s emerging from this conversation that I had not fully grokked before is that the process of having to think more explicitly about links is part of the work, and it might be part of the value. Maybe that analog system adds just enough friction to become an important part of the work itself.

The value of friction

Sönke: Yeah, I think that’s true. When you don’t have to put effort into linking, you tend to link too much and you tend to link to the things that pop into your mind most quickly. If you have to put a little bit more effort and time into it, you think more on the content level and you are much more selective with what you’re linking to.

And I think you really put it well. The linking work is basically the thinking work. It’s not housekeeping; it is actually the work. And that becomes obvious when you think about, “okay. How do I describe the connection between two notes?” You have to use words that form an argument. You have to use the word like, “on the other hand,” or a phrase like, “on the other hand.” Or, “extending on that thought, see also,” or, “another aspect of this is,” or, “this poses the question.” So, you turn almost like a bullet point list of interesting ideas into something much more coherent.

One of the reasons I wrote this book is because I wanted to give my students something that they could actually use. But also out of frustration that I felt I get a lot of papers and essays that feel like disconnected collections of ideas. And where little effort is put into building a coherent argument. And I think that… or I felt this has something to do with the way students often take notes. They have a phase where they read a lot. They copy quotes they like, they collect ideas they like. They have the bookmarks. And then they assemble it into something. But at that point it’s almost too late to get back to the original argument, see how the context is related to the context of your own argument, how to translate between these two contexts.

And if you change the way you take notes so it’s not a collection, but a reflection on paper of an ongoing thinking process, then hopefully it will also improve the quality of the papers I have to read/ so that was one of the ideas. And another idea connected with that is that I often have the impression that students shy away from expressing their own ideas and their own judgment of what they read, so they sometimes write about ideas that when you ask them, they haven’t fully grasped or don’t fully agree with but feel they don’t have the authority to engage fully with the argument of some established writer. And that also is reflected in the way notes are taken.

So, if you use a system that forces you to make explicit what you think about something and make explicit how something someone else has written is related to what you are thinking yourself, I think it helps with connecting these ideas of others with your own thinking. So it feels like bringing it closer together, so…

Collecting, connecting, and contextualizing

Jorge: I really like this distinction that you’re bringing up. And one way to think about it might be… and I’m just going to reflect what I’m hearing: a lot of note-taking — particularly around things like reading — so much of this is, at least for me, about ideas that I encounter in the world that trigger ideas of my own. And I think of that somehow as collecting. There’s a second step, which you’ve already covered, which is around connecting. So you’ve collected certain ideas and there might be relationships that emerge between them, and you make those connections explicit. What I’m hearing is that there’s this third step that is very important, which is about contextualizing. So that we know why those connections matter to you. It’s not just about assembling these sets of ideas, whether your own ideas or other people’s ideas, it’s also about telling us why this set makes sense and why it matters, right?

Sönke: Right. Yeah, and I think this is related to maybe the most important aspect of note-taking in general, and that is: if you want to change your mind about something, you have to get some distance to that. And it’s very difficult to change your mind about something when it’s only in your mind. And the moment you write it down, you get literally some distance to it and it makes it much more easier, to deal with that as if it were a thought of someone else. And not writing explicitly what you think about something — what you read or have on your notes — makes it very difficult to connect to that as something that it’s not just in the background and shaping your ideas, but it is something you can actually discuss and put into contrast with other people’s ideas. So getting this kind of distance to what is only implicit in the beginning is maybe the most important aspects of note taking in general.

Jorge: Well, that’s a very interesting way to think about it. The way that I’ve been approaching it and how I’ve thought about it in the past is informed by ideas like this whole field around embodied cognition and the notion that the note becomes an extension of your mind somehow, a way for you to leverage the environment as part of your thinking apparatus. But what you’re saying here strikes me as being another aspect of that, which is that when the idea is captured — in the world, outside of your mind — all of a sudden it’s kind of on a level playing field with other ideas that are out there. So you’re no longer personalizing it somehow.

Note-taking as thinking

Sönke: Yeah. That’s nicely put. And I think it resonates with the idea of the external mind. I mean, you had Annie Murphy Paul on your podcast. So when I read her book, I thought, yeah, that’s very much a description of what I feel is a conceptual change in thinking about note-taking that it’s much less thought today as an afterthought and much more of an integrated element of the thought process itself. And I think that is reflected in philosophical concepts about thinking.

We used to think about thinking clearly as something that’s in your head and writing as something that follows the thinking process. It’s kind of a recording of what has happened before. So there’s a representation of your thinking. But this representational paradigm is being discussed in philosophy for a long time now. But I feel there are so many practical implications that are not being discussed or now being discussed coming from a very different point of view and Annie Murphy Paul describes how in different areas there is a change in how we think about the environment and how the environment is not just shaping our ideas, but how thinking itself must be thought as being at the same time inside and outside our mind. It doesn’t really work seeing writing as an afterthought. Because it’s not.

Jorge: Yeah. And in your book, I remember you talk about writing to think. Somehow, there is this intimate connection between the writing process and thinking. They one thing I wanted to ask you about. Sometimes, when I talk to people about this and I tell them that I’m working on a book on the subject, the idea of connected note taking and maintaining… I’m going to try to put myself in their shoes: when people hear ideas like these, I think they imagine, perhaps rightly so, a very elaborate system that requires a lot of effort.

And I have two questions about that and I’m just going to pose them now and maybe we can discuss one, either, or both. The first is: who is this for? Is this primarily something for academics to be concerned with, or people who are maybe writing especially nonfiction? Or does it have broader applicability? Let’s start there with that; that would be a first take on this.

Who is note-taking for?

Sönke: Well, it’s fair to say that I wrote the book specifically for students, young academics and nonfiction writers. For people who deal with a lot of information, who read a lot, you need to process all that information and turn that into new written output. It’s part of my own learning process that the audience for the book… the people the book resonated with and also academics and nonfiction writers, but primarily people from professions where an emphasis is on the continuity of learning, and where they long for a system that lasts longer than the one particular project they’re working on because they feel they have bigger arches in their career and the difference between the professional life and the personal interest is often blurred anyway.

So they are looking for a more integrated approach. And in a way it answers a very basic want. And that is: well, when I read a lot; I also want to remember some of it. And I think we all know this experience that we look at the books we read and are astonished how little we are able to recollect from that. We do feel and know that the books we read kind of shaped our lives. And we are different because we read them. But it’s difficult to retrieve the information. And if you just highlight stuff or write comments in the margins of the books, you don’t actually go back and read the book again if you needed too. First of all, you need to remember in which book a particular idea was.

So having a system in place that, of course, cannot capture everything you have ever encountered! But captures the main ideas and keeps them in play. Because the system forces you, or nudges you, to connect new ideas with old ideas, which make old ideas resurface again and again. I think it’s a healthy dose of conservatism that counterbalances our excitement about new ideas.

So there’s nothing wrong with new, exciting ideas. But it’s even better when you have a system in place where you check how that connects to what you have previously thought. And just check is it really that new? Or is it new? And in which way, exactly? Is it answering a different question? Does it change the question? Is it a new answer to the same question? And when you just read without writing and connecting, you don’t get these prompts to these kinds of questions. But I think these are the important questions because everything we read in the past, is not automatically useless after a while. We just tend to forget it and focus on the new. And maybe that is in the second part of the answer to your question.

Maybe it’s especially useful for people who deal with information that lasts a bit. I have had discussions with people from the medical profession, especially doctors who struggle a lot with information overload and long for system that works. But I think the zettlekasten might not be the perfect fit here because you really need to be up to date and the timestamp of a fact is extremely important. And the system is developed by someone who deals with sociological ideas and more timeless questions. So I would say the ideal audience for these ideas are people who think in longer timeframes. Does that make sense?

Jorge: Yeah! Yes, it definitely does. And I really love this phrase you use. The phrase, “people who have this emphasis on the continuity of learning.” What that brought to mind is that a system like this helps establish a perhaps healthier balance between long-term knowledge or more long-lasting knowledge or knowledge that stands the test of time over the primacy of novelty, which is so prevalent in today’s media environments. So it’s like, if you find yourself overwhelmed with all the stuff coming at you, this is a good opportunity to dip into a system where you are building something that is longer lived somehow. And that brings me to the second part of the question. And this is my second to last question for you… This phrase, “people who care about the continuity of learning,” I think opens up the audience of people who might be interested in this quite a bit. What are your recommendations for people who are looking to get started without feeling overwhelmed?

I would expect that reading your book would be an important first step. But there are all these tools out there currently that promise… well, this might be an unfair characterization. I don’t know that any of them are making explicit promises about what you’re going to get. But there’s this implicit idea that all you need is a tool. All you need is the new shiny note-taking app. But my sense in working with these things and experimenting with them over the years is that having the right tools is one thing, but it’s more about certain practices and perhaps mindsets, when using the tools. And I was just wondering if you had any tips for people who maybe they’ve discovered a new tool, or they’re looking to find out about how to do this for themselves. Do you have any recommendations to help them get started? Knowing that this can be very overwhelming, right?

Embrace the process

Sönke: Right. I think you’re completely right. The tools are important and they make a difference, and if you choose one tool, you will work differently than with another tool. Sometimes people talk about tools as if they are interchangeable. And I don’t think they are. But you can use every tool in all kinds of ways. And I fully agree that the most important ingredients for working a system is to understand the core concepts and principles. And having an idea about what you want to achieve with that. Because you can easily use all the tools available as just a dumping ground for ideas and you just collect stuff, and it won’t be useful over time.

So you have to get used to making intelligent connections which are descriptive and will be useful in a year’s time when you forgot the context when you’ve written them down. And that is a learning process. And there are feedback loops, which I find helpful, kind of built in. When I wrote two short notes, after a while when I stumble upon them, I kind of see I need more context, so they get a little bit longer. So it’s nothing wrong about being aware that’s the learning process.

I’m currently preparing an online course based on Obsidian and probably Roam as well. So these two tools share the emphasis on bidirectional linking, which I think is very apt for that system. And I found both very simple in the setup. And they both come with the difficulty that they come with little structure. So you have to invent the structure yourself. And that is the reason I feel, beyond the book, it could be helpful to guide people into setting their zettlekasten and the principles in these tools up so you get a headstart.

But then people adapt their systems to their needs. And I think that’s kind of the beauty of it. And you shouldn’t expect that someone can hand you the perfect system or the perfect tool, and all you need to do is react to that and just use it without thinking about how to structure it. Because as you said earlier, the way you structure your ideas is part of the learning and part of the thinking process. And if you deal with a topic that is very hierarchically structured, you will end up with a more hierarchical structure. And if you think about questions which are very open, interdisciplinary… it’s much more apt to put the emphasis on the bottom up process and see what structure bubbles up. But there is no rule that you can just apply and you will have the perfect workflow set up.

Jorge: And I would say to folks, just to try to answer the question from a different angle, or to reflect back to you. What I’m hearing there is the tools and practices matter, but it’s more important to know why you’re doing it and to have a certain set of principles and the right mindset. And I will say that I think that your book is a great place for folks to pick up, /particularly on the principles side of things. It’s a short read and it’s jampacked with really valuable ideas. So thank you for sharing the book with us, and thank you for sharing with us today. Where can folks follow up with you?


Sönke: I’m on Twitter. I rarely tweet, so maybe the best is to look up the website, takesmartnotes.com and go from there.

Jorge: Great. Well, I will include a link to that and to your Twitter account in the show notes. Thank you so much for being with us today.

Sönke: Thank you so much for having me.