"But now, how do you arrange your documents?"
Intellectual Workflow Part 1: Introduction to the Zettelkasten
‘Yes,’ said Mr Brooke, with an easy smile, ‘but I have documents. I began a long while ago to collect documents. They want arranging, but when a question has struck me, I have written to somebody and got an answer. I have documents at my back. But now, how do you arrange your documents?’
‘In pigeon-holes, partly,’ said Mr Casaubon, with rather a startled air of effort.
‘Ah, pigeon-holes will not do. I have tried pigeon-holes, but everything gets mixed in pigeon-holes. I never know whether a paper is in A or Z.’
‘I wish you would let me sort your papers for you, uncle,’ said Dorothea. ‘I would letter them all, and then make a list of subjects under each letter.’
Mr Casaubon gravely smiled approval, and said to Mr Brooke, ‘You have an excellent secretary at hand, you perceive.’
‘No, no,’ said Mr Brooke, shaking his head; ‘I cannot let young ladies meddle with my documents. Young ladies are too flighty.’
—George Eliot, Middlemarch
I have always struggled with knowledge management. I have gone through countless iterations of note-keeping in notebooks, on notepads, on index cards, on looseleaf. I have annotated books and I have annotated my own notes. I have developed elaborate numbering and lettering systems, highlighted everything in sight, gone through piles of sticky notes, and have created countless files, physical and digital, only to never revisit them again (nor to have any ability to remember any of the information in them a few months later). In university, I wrote many successful papers, including a 60-page undergraduate thesis, but they always seemed to come together through some combination of happenstance, caffeine, and panic.
Within the last few years, long after my formal educational years came to an end, I learned about commonplace books, bullet journals, and Charlotte Mason-style written narrations, and my intellectual life became a little more organised. This past summer, I read A.G. Sertillanges’ The Intellectual Life for the first time, and his description of note-keeping on individual slips of paper left me intrigued, but still unsure of how I could apply it to my own intellectual life.
And then, one January evening earlier this year, when I was browsing Pinterest instead of doing something actually worthwhile, I stumbled upon a strangely-named and highly-intriguing note-making and thinking tool. It is now my great pleasure to introduce you to the simple tool that has enlivened and organised my intellectual life in ways I had come to believe impossible: the zettelkasten.
The zettelkasten method is most commonly associated with 20th-century German social scientist Niklas Luhmann. Luhmann was exceptionally prolific, and he credited his productivity to his zettelkasten, or slip-box. The zettelkasten is a deceptively simple idea: notes are collected on individual slips of paper, each of which is assigned a unique permanent identifier which can be used to locate the note and to create connections between individual notes. It is this ability to link easily among different ideas that gives the system its power.1
If you think this sounds a bit like how the internet works, and in particular how websites like Wikipedia work, you’re not wrong. The zettelkasten is, in essence, a hypertext: a system of interlinked documents. Luhmann’s zettelkasten was on paper, however, given that much of his life was lived before the internet was a reality.
According to A.G. Sertillanges, in intellectual work, it is not having an abundance of ideas that matters; rather, true value lies in the discovery of essential connections underlying the subject of investigation.2 The zettelkasten facilitates the discovery of such connections, and the resulting network of associated ideas in turn facilitates the writing and thinking processes.
The zettelkasten itself has only three essential components: the notes, an index, and some method for managing and keeping track of references. Modern technology allows us to choose to have a physical, digital, or mixed zettelkasten, as best suits our own personal needs. Regardless of our choice, however, the zettelkasten will still consist of the three aforementioned components, so let’s take a closer look at each one.
The notes are the heart of the zettelkasten. Each note should contain only one idea, written succinctly. If written on physical note-cards, only one side of the card should be used, in order to facilitate later reading. The notes should be written in the learner’s own words, and should be written in such a way that they will be understandable years in the future, when their original context has been forgotten (although it is generally wise to cite the original source in the note, if the note does not originate from personal thought or experience). These stipulations are not arbitrary; they are in fact crucial to the overall functionality of the zettelkasten. Rewriting ideas in one’s own words, rather than copying them from the original source, verifies and deepens understanding. And if the zettelkasten is to be useful, notes must be comprehensible in the long-term.
Each note should be assigned a unique identifier. The identifier itself can—and many would argue, should—be, of itself, meaningless. Luhmann used a combination of numbers and letters, and many have followed in his pattern. The identifier acts primarily as an address—the location where the note can be found—and is not meant to indicate any sort of categorisation or hierarchy. That said, the identifier can indicate relationships between different notes. Let’s explore this idea with a practical example.
Suppose I’m reading a book about horses. I decide that I want the first note in my zettelkasten to be a basic physical description of a horse. I write something like this:
“A horse is a four-legged, hoofed animal with a mane and tail, and a body covered in hair. Horses are similar in shape and general appearance to donkeys, zebras, and mules. They usually measure around 5 feet high at the top of the shoulder, with strong, muscular bodies.”
I now assign this note to the identifier 1.1, which I write in the upper-left-hand-corner of the note card. I return to my book. A few pages later, I come across new information that I want to include in my zettelkasten. I write the following:
“Most horses have four gaits: walk, trot, canter, and gallop. Some particular breeds of horse have additional gaits, such as the tölt of the Icelandic horse.”
This note closely relates to my first note, so I give it the identifier 1.2, and I return again to my book. Note 1.3 soon follows:
“Horses are used in a number of Olympic sports, including show jumping, dressage, and eventing.”
All is well, until I learn this next fact:
“The trot is a two-beat gait, where diagonal pairs of legs move together. In speed, it is between the walk and the canter.”
It seems that this note should directly follow note 1.2, which was also about horse gaits—but we already have a note 1.3! What do we do? This is where letters come into play. My note about the trot is assigned the identifier 1.2a, and is placed directly behind note 1.2. Suppose next I write about the canter in note 1.2b, only later to happen upon yet another fact about trotting. I can insert it behind note 1.2a by giving it the identifier 1.2a1. Through this appending and iterating of letters and numbers, we can place new cards precisely where we want them.
Now, I happen also to be reading other books at the same time as my horse book. Maybe I make a note that Alexander the Great was a student of Socrates. This doesn’t have anything to do with my chain of notes about horses, so I give it an identifier 2.1 and continue on in my reading. I make a number of additional notes about Alexander, and then I learn about his horse Bucephalus. Say this note is given the identifier 2.5. I realise, however, that I have a whole chain of information about horses, so at the bottom of the note about Alexander and Bucephalus, I write something like this:
“For more on horses, see 1.1.”
I have now linked my note about Alexander and Bucephalus to my notes about horses. It is a simple and obvious connection, but it is a connection all the same, and recording this link makes it easy to navigate between topics.
In this same way, I continue to add notes to my zettelkasten as I read and learn. If a new note relates to one already contained in my slip-box, I can place the new note right behind the one it relates to. If a new note is its own new idea, I place it behind the last note in the slip-box. And if the note is associated with other ideas in the slip-box, I can link the notes together using their unique identifiers. In this way, I begin to develop a network of interconnected ideas.
This is the basic procedure for building up the zettelkasten. There are variations on this method, but they all come down to the same fundamental actions: write a note, give it an identifier, and link it to other notes.
One of the strengths of the zettelkasten is its capacity to accommodate different types of information. It is equally capable of containing complicated and simple ideas, interesting facts, personal thoughts and ideas, ideas derived from texts, ideas derived from conversation, and, in general, anything else we want to keep track of or incorporate into our thinking. All of these different types of information can play a critical role in our thinking processes and lead us to new connections and new ways of understanding reality. When we derive our ideas from external sources, however, we will typically want to keep track of these sources, and that is where the second element of the zettelkasten comes into play.
Because many of our notes will derive directly from our reading, we must include some method for managing sources in our zettelkasten. Some people will choose to use a digital reference manager such as Zotero, even if they use physical note-cards for the bulk of their zettelkasten. Others will have an entirely digital zettelkasten, using one or more programs to link their ideas and references. Some, like me, will have an entirely physical zettelkasten, and will store references on note-cards, just as the notes themselves are on note-cards. The exact method doesn’t really matter; the key is to be able to link the idea on a note to the original source of the idea in a straight-forward and easy-to-maintain fashion.
As we continue to add new ideas to our zettelkasten, it will inevitably become more difficult to locate any particular idea we are searching for. This is where the third element of the zettelkasten, the index, comes in. Normally when we think of an index, we think of something that lists all of the instances of that particular idea within a source. The index for the zettelkasten functions a bit differently. Instead of trying to list all of the notes that fall under a particular topic, we want the index for our zettelkasten to give us a good entry-point into our web of thought. Therefore, a typical zettelkasten index will only include one or two identifiers next to each subject. Continuing our example above, then, for the concept of “Horse” in the index for my zettelkasten, I need only link to card 1.1. From there, I can navigate through my zettelkasten based on the links I have put on the individual notes. This is a very different way of exploring a topic, but a very good one if you want to follow a particular chain of thought or find novel connections. The index is not meant to be exhaustive, and the bulk of the work is always meant to take place within the notes in the zettelkasten, and not within the index itself.
This, then, is the basic idea of the zettelkasten: a collection of personal, interconnected notes, organised to facilitate the discovery of new associations and to support the processes of thinking and writing. There is, of course, much more to be said than I could fit into this introduction, and there are plenty of people out there who have said what I said, and more, better than I have written it here.
The obvious remaining question, though, is why? Why the zettelkasten? What is it about a box of notes that I, and many other people, have found so revolutionary in our intellectual lives?
Many advantages have been widely noted. The zettelkasten excels in helping its user to find new connections between ideas. The zettelkasten supports memory by frequently re-exposing its user to the ideas contained therein. The zettelkasten encourages comprehension through its insistence upon succinct rewording of ideas by its user. The zettelkasten facilitates accumulation and retrieval of ideas over time, and in contrast to other means of storing information, it becomes more powerful as it grows, rather than more confusing and difficult to use. All of these things are true, and all of them speak to the strength of the method. But I think there is something more fundamental happening—something I haven’t seen discussed:
The structure of the zettelkasten corresponds to the structure of the very fabric of truth itself, as well as to our natural ways of experiencing reality and engaging with it.
Truth itself is an interconnected network of particular truths—fragments of the whole. All truth originates from its Creator, and all that exists forms one complex fact or truth, which is composed of infinite particular facts in relationship to one another. Although there are no real or natural limits between the different parts of the whole truth, the human mind simply cannot take in this massive whole all at once, and so we approach the entirety through abstractions—the particular facts, ideas, and their relationships that underlie the whole.3
In the zettelkasten, individual ideas and particular truths are abstracted from their original contexts and are interconnected organically in a non-hierarchical network, without the imposition of artificial categories or limits. The individual notes are fragments of a larger integrated system of thought.
Much like reality, the human memory is typically organised into networks of interconnected ideas, rather than into topics or hierarchies. When we want to understand something new, we generally try to connect the new idea to what we already know. When we want to retrieve something from our memory, we usually do so by calling to mind ideas associated with it.
Again, the zettelkasten mirrors this functioning. The existing notes are organised into networks of interconnected ideas. When we want to add a new idea, we try to connect it to ideas already present in the zettelkasten. When we want to retrieve something from the zettelkasten, we find it through the other notes that are associated with it.
When we think, although we tend to credit only our minds, our thinking often extends through and beyond our bodies. Consider, for example, how we physically rearrange Scrabble tiles when we’re trying to come up with new words, or how a sports coach may plan out his strategy with figurines or illustrations. Thinking extends beyond the mind.
The zettelkasten allows us to externalise and manipulate our ideas outside of the mind. With a physical zettelkasten in particular, we can manipulate our notes, arranging and rearranging them into a variety of new configurations. Thinking extends beyond the mind.
The zettelkasten isn’t, in the end, a miracle. It can’t do your thinking for you. It won’t make you smarter or write your book while you nap on the couch. It’s probably not even all that helpful for learning something like a new language or sport or handicraft. But if you have struggled with knowledge management like I have, it may be just the tool that you’re looking for to organise your mind, advance your thinking, and stumble upon new associations that are the pinnacle of the learning process and a source of deep joy.
I hope you’ve enjoyed this first part of my series on intellectual workflow. In part 2, I will give you a closer look at my personal zettelkasten and discuss some of the decisions I have made about it and the practices I have adopted in using it. Part 3 will discuss intellectual workflow as a whole, including the role of the zettelkasten in the overall workflow.
If you would like to learn more about the zettelkasten, I have included some suggested reading below. If you have any questions, I invite you to leave them in comments, and I will do my best to answer them or to direct you to someone else who can give an answer. And if this article was helpful or interesting to you, please consider sharing it with someone else who might enjoy it and subscribing to my substack newsletter, published every other Thursday.
I’d love to hear your thoughts on intellectual workflow! Do you have an intellectual workflow? What is it like? Are you happy with your workflow, or are there things you struggle with? Let’s get the discussion started!
Further Reading:
How to Take Smart Notes. One Simple Technique to Boost Writing, Learning, and Thinking by Sönke Ahrens is widely-considered to be the go-to book on the zettelkasten method. Although partly motivational, it also gives a broad, technologically-agnostic, overview of the zettelkasten method and process.
Zettelkasten.de is the best source on the internet for all things zettelkasten. The “Getting Started” page will teach you everything you need to know to begin your own zettelkasten.
“Communicating with Slip Boxes” is an English translation of Niklas Luhmann’s own account of his use of the zettelkasten.
Bob Doto has written some really helpful articles about the zettelkasten. I found his essay on the use of folgezettel to be particular helpful in developing my own note-identifier assignment procedures.
Chris Aldrich has some great articles about various aspects of the zettelkasten method and about personal knowledge management in general. He uses a physical zettelkasten, which seems to be the less-common choice these days, so he offers some unique insights for anyone interested in choosing paper over digital.
Sönke Ahrens, How to Take Smart Notes: One Simple Technique to Boost Writing, Learning and Thinking, 2nd edition, revised and expanded edition (Hamburg, Germany: Sönke Ahrens, 2022).
A.G. Sertillanges, The Intellectual Life: Its Spirit, Conditions, Methods, trans. Mary Ryan (Washington, DC: Catholic University of America Press, 1998), 129-130.
c.f. Sertillanges, The Intellectual Life: Its Spirit, Conditions, Methods, 30-31; John Henry Newman, The Idea of a University (Notre Dame, IN: University of Notre Dame Press, 1982), 33-34.