This paper by Jason Lustig on Gotthard Deutsch’s was fascinating: While there’s an implication that its use didn’t make him as productive (from a writing perspective) as Niklas Luhmann or S.D. Goitein, I might suggest that it made him a more productive thinker and teacher, which in turn bore results in the form of his students who also picked up the practice from him.

On the Jokerzettel: An Apocalyptic Interpretation of Luhmann’s note ZKII 9/8j

Niklas Luhmann’s Jokerzettel 9/8j

Many have asked about the meaning of Niklas Luhmann’s so-called jokerzettel over the past several years.

9/8j Im Zettelkasten ist ein Zettel, der das
Argument enthält, das die Behauptungen
auf allen anderen Zetteln widerlegt.

Aber dieser Zettel verschwindet, sobald man
den Zettelkasten aufzieht.
D.h. er nimmt eine andere Nummer an,
verstellt sich und ist dann nicht zu finden.

Ein Joker.

—Niklas Luhmann, ZK II: Zettel 9/8j


9/8j In the slip box is a slip containing the argument that refutes the claims on all the other slips. But this slip disappears as soon as you open the slip box. That is, he assumes a different number, disguises himself and then cannot be found. A joker.

An Apocalyptic Interpretation

Here’s my slightly extended interpretation, based on my own practice with several thousands of cards, about what Luhmann meant:

Imagine you’ve spent your life making and collecting notes and ideas and placing them lovingly on index cards. You’ve made tens of thousands and they’re a major part of your daily workflow and support your life’s work. They define you and how you think. You agree with Friedrich Nietzsche’s concession to Heinrich Köselitz that “You are right — our writing tools take part in the forming of our thoughts.” Your time is alive with McLuhan’s idea that “The medium is the message.” or his friend John Culkin‘s aphorism, “We shape our tools and thereafter they shape us.”

Eventually you’re going to worry about accidentally throwing your cards away, people stealing or copying them, fires (oh! the fires), floods, or other natural disasters. You don’t have the ability to do digital back ups yet. You may ask yourself, can I truly trust my spouse not to destroy them? What about accidents like dropping them all over the floor and needing to reorganize them or worse, what if the ghost in the machine should rear its head?

You’ll fear the worst, but the worst only grows logarithmically in proportion to your collection.

Eventually you pass on opportunities elsewhere because you’re worried about moving your ever-growing collection. What if the war should obliterate your work? Maybe you should take them into the war with you, because you can’t bear to be apart?

If you grow up at a time when Schrödinger’s cat is in the zeitgeist, you’re definitely going to have nightmares that what’s written on your cards could horrifyingly change every time you look at them. Worse, knowing about the Heisenberg Uncertainly Principle, you’re deathly afraid that there might be cards, like electrons, which are always changing position in ways you’ll never be able to know or predict.

As a systems theorist, you view your own note taking system as a input/output machine. Then you see Claude Shannon’s “useless machine” (based on an idea of Marvin Minsky) whose only function is to switch itself off. You become horrified with the idea that the knowledge machine you’ve painstakingly built and have documented the ways it acts as an independent thought partner may somehow become self-aware and shut itself off!?!

And worst of all, on top of all this, all your hard work, effort, and untold hours of sweat creating thousands of cards will be wiped away by a potential unknowable single bit of information on a lone, malicious card; your only recourse is suicide, the unfortunate victim of dataism.

Of course, if you somehow manage to overcome the hurdle of suicidal thoughts, and your collection keeps growing without bound, then you’re sure to die in a torrential whirlwind avalanche of information and cards, literally done in by information overload.

But, not wishing to admit any of this, much less all of this, you imagine a simple trickster, a joker, something silly. You write it down on yet another card and you file it away into the box, linked only to the card in front of it, the end of a short line of cards with nothing following it, because what could follow it? Put it out of your mind and hope your fears disappear away with it, lost in your box like the jokerzettel you imagined. You do this with a self-assured confidence that this way of making sense of the world works well for you, and you settle back into the methodical work of reading and writing, intent on making your next thousands of cards.

A note about my article on Goitein with respect to Zettelkasten Output Processes

Not long ago I made a Call for Model Examples of Zettelkasten Output Processes. To answer a part of that call and to highlight my own reading, note taking, and writing process, in the production of writing S.D. Goitein’s Card Index, I’ve included red # hyperlinks to all of the available digital notes I took while doing my research which is synthesized there. The interested reader can then look back to see the date and timestamps of all of my original notes and compare them if they wish to the final text of the piece. One will notice that most of the Goitein-specific portions occurred on two consecutive days while other portions were tied in from notes taken over the past two years including a few which may have been older, but revised for import.

I’m hoping that this example will give the aspiring interested note takers, commonplacers, and zettelkasten maintainers a peek into a small portion of my own specific process if they’d like to look more closely at such an example.

Following the reading and note taking portions of the process, I spent about 5 minutes scratching out a brief outline for the shape of the piece onto one of my own 4 x 6″ index cards. I then spent 15 minutes cutting and pasting all of what I felt the relevant notes were into the outline and arranging them. I then spent about two hours writing and (mostly) editing the whole. In a few cases I also cut and pasted a few things from my digital notes which I also felt would be interesting or relevant (primarily the parts on “notes per day” which I had from prior research.) All of this was followed by about an hour on administrivia like references and HTML formatting to put it up on my website. While some portions were pre-linked in a Luhmann-ese zettelkasten sense, other portions like the section on notes per day were a search for that tag in my digital repository in which allowed me to pick and choose the segments I wanted to cut and paste for this particular piece.

From the outline to the finished piece I spent about three and a half hours to put together the 3,500 word piece. The research, reading, and note taking portion took less than a day’s worth of entertaining diversion to do including several fun, but ultimately blind alleys which didn’t ultimately make the final cut.

For the college paper writers, this entire process took less than three days off and on to produce what would be the rough equivalent of a double spaced 15 page paper with footnotes and references. Naturally some of my material came from older prior notes, and I would never suggest one try to cram write a paper this way. However, making notes on a variety of related readings over the span of a quarter or semester in this way could certainly allow one to relatively quickly generate some reasonably interesting material in a way that’s both interesting to and potentially even fun for the student and which could potentially push the edges of a discipline—I was certainly never bored during the process other than some of the droller portions of cutting/pasting.

While the majority of the article is broadly straightforward stringing together of facts, one of the interesting insights for me was connecting a broader range of idiosyncratic note taking and writing practices together across time and space to the idea of statistical mechanics. This is slowly adding to a broader thesis I’m developing about the evolving life of these knowledge practices over time. I can’t wait to see what develops from this next.

In the meanwhile, I’m happy to have some additional documentation for another prominent zettelkasten example which resulted in a body of academic writing which exceeds the output of Niklas Luhmann’s own corpus of work. The other outliers in the example include a significant contribution to a posthumously published book as well as digitized collection which is still actively used by scholars for its content rather than for its shape. I’ll also note that along the way I found at least one and possibly two other significant zettelkasten examples to take a look at in the near future. The assured one has over 15,000 slips, apparently with a hierarchical structure and a focus on linguistics which has some of the vibes of John Murray’s “slip boxes” used in the creation of the Oxford English Dictionary.

S.D. Goitein’s Card Index (or Zettelkasten)


Scholar and historian S.D. Goitein built and maintained a significant collection of over 27,000 notes in the form of a card index (or zettelkasten1) which he used to fuel his research and academic writing output in the mid to late twentieth century. The collection was arranged broadly by topical categories and followed in the commonplace book tradition though it was maintained on index cards. Uncommon to the space, his card index file was used by subsequent scholars for their own research and was ultimately digitized by the Princeton Geniza Project.

Introduction to S.D. Goitein and his work

Shelomo Dov Goitein (1900-1985) was a German-Jewish historian, ethnographer, educator, linguist, Orientalist, and Arabist who is best known for his research and work on the documents and fragments from the Cairo Geniza, a fragmented collection of some 400,000 manuscript fragments written between the 6th and 19th centuries.

Born in Burgkunstadt, Germany in 1900 to a line of rabbis, he received both a secular and a Talmudic education. At the University of Frankfurt he studied both Arabic and Islam from 1918-1923 under Josef Horovitz and ultimately produced a dissertation on prayer in Islam. An early Zionist activist, he immigrated to Palestine where he spent 34 years lecturing and teaching in what is now Israel. In order to focus his work on the Cairo Geniza, he moved to Philadelphia in 1957 where he lived until he died on February 6, 1985.

After becoming aware of the Cairo Geniza’s contents, S.D. Goitein ultimately devoted the last part of his life to its study. The Geniza, or storeroom, at the Ben Ezra Synagogue was discovered to hold manuscript fragments made of vellum, paper, papyrus, and cloth and written in Hebrew, Arabic, and Aramaic covering a wide period of Middle Eastern, North African, and Andalusian Jewish history. One of the most diverse collections of medieval manuscripts in the world, we now know it provides a spectacular picture of cultural, legal, and economic life in the Mediterranean particularly between the 10th and the 13th centuries. Ultimately the collection was removed from the Synagogue and large portions are now held by a handful of major research universities and academic institutes as well as some in private hands. It was the richness and diversity of the collection which drew Goitein to study it for over three decades.

Research Areas

Goitein’s early work was in Arabic and Islamic studies and he did a fair amount of work with respect to the Yemeni Jews before focusing on the Geniza.

As a classically trained German historian, he assuredly would have been aware of the extant and growing popularity of the historical method and historiography delineated by the influential works of Ernst Bernheim (1899) and Charles Victor Langlois and Charles Seignobos (1898) which had heavily permeated the areas of history, sociology, anthropology, and the humanities by the late teens and early 1920s when Goitein was at university.

Perhaps as all young writers must, in the 1920s Goitein published his one and only play Pulcellina about a Jewish woman who was burned at the stake in France in 1171. [@NationalLibraryofIsrael2021] # It is unknown if he may have used a card index method to compose it in the way that Vladimir Nabokov wrote his fiction.

Following his move to America, Goitein’s Mediterranean Society project spanned from 1967-1988 with the last volume published three years after his death. The entirety of the project was undertaken at the University of Pennsylvania and the Institute for Advanced Study to which he was attached. # As an indicator for its influence on the area of Geniza studies, historian Oded Zinger clearly states in his primer on research material for the field:

The first place to start any search for Geniza documents is A Mediterranean Society by S. D. Goitein. [@Zinger2019] #

Further gilding his influence as a historian is a quote from one of his students:

You know very well the verse on Tabari that says: ‘You wrote history with such zeal that you have become history yourself.’ Although in your modesty you would deny it, we suggest that his couplet applies to yourself as well.”
—Norman Stillman to S.D. Goitein in letter dated 1977-07-20 [@NationalLibraryofIsrael2021] #

In the early days of his Mediterranean Society project, he was funded by the great French Historian Fernand Braudel (1902-1985) who also specialized on the Mediterranean. Braudel had created a center in Paris which was often referred to as a laboratoire de recherches historiques. Goitein adopted this “lab” concept for his own work in American, and it ultimately spawned what is now called the Princeton Geniza Lab. [@PrincetonGenizaLab] #

The Card Index


In addition to the primary fragment sources he used from the Geniza, Goitein’s primary work tool was his card index in which he ultimately accumulated more than 27,000 index cards in his research work over the span of 35 years. [@Rustow2022] # Goitein’s zettelkasten ultimately consisted of twenty-six drawers of material, which is now housed at the National Library of Israel. [@Zinger2019] #.

Goitein’s card index can broadly be broken up into two broad collections based on both their contents and card sizes:

  1. Approximately 20,000 3 x 5 inch index cards2 are notes covering individual topics generally making of the form of a commonplace book using index cards rather than books or notebooks.
  2. Over 7,000 5 x 8 inch index cards which contain descriptions of a fragment from the Cairo Geniza. [@Marina2022] [@Zinger2019] #

The smaller second section was broadly related to what is commonly referred to as the “India Book” # which became a collaboration between Goitein and M.A. Friedman which ultimately resulted in the (posthumous) book India Traders of the Middle Ages: Documents from the Cairo Geniza “India Book” (2007).

The cards were all written in a variety of Hebrew, English, and Arabic based on the needs of the notes and the original languages for the documents with which they deal.

In addition to writing on cards, Goitein also wrote notes on pieces of paper that he happened to have lying around. [@Zinger2019] # Zinger provides an example of this practice and quotes a particular card which also shows some of Goitein’s organizational practice:

 In some cases, not unlike his Geniza subjects, Goitein wrote his notes on pieces of paper that were lying around. To give but one example, a small note records the location of the index cards for “India Book: Names of Persons” from ‘ayn to tav: “in red \ or Gray \ box of geographical names etc. second (from above) drawer to the left of my desk 1980 in the left right steel cabinet in the small room 1972” is written on the back of a December 17, 1971, note thanking Goitein for a box of chocolate (roll 11, slide 503, drawer13 [2.1.1], 1191v). 

This note provides some indication of some of his arrangements for note taking and how he kept his boxes. They weren’t always necessarily in one location within his office and moved around as indicated by the strikethrough, according to his needs and interests. It also provides some evidence that he revisited and updated his notes over time.

In Zinger’s overview of the documents for the Cairo Geniza, he also provides a two page chart breakdown overview of the smaller portion of Goitein’s 7,000 cards relating to his study of the Geniza with a list of the subjects, subdivisions, microfilm rolls and slide numbers, and the actual card drawer numbers and card numbers. These cards were in drawers 1-15, 17, and 20-22. [@Zinger2019] #


Zinger considers the collection of 27,000 cards “even more impressive when one realizes that both sides of many of the cards have been written on.” [@Zinger2019] Goitein obviously broke the frequent admonishment of many note takers (in both index card and notebook traditions) to “write only on one side” of his cards, slips, or papers. # This admonishment is seen frequently in the literature as part of the overall process of note taking for writing includes the ability to lay cards or slips out on a surface and rearrange them into logical orderings before copying them out into a finished work. One of the earliest versions of this advice can be seen in Konrad Gessner’s Pandectarum Sive Partitionum Universalium (1548).

Zinger doesn’t mention how many of his 27,000 index cards are double-sided, but one might presume that it is a large proportion. # Given that historian Keith Thomas mentions that without knowing the advice he evolved his own practice to only writing on one side [@Thomas2010], it might be interesting to see if Goitein evolved the same practice over his 35 year span of work. #

The double sided nature of many cards indicates that they could have certainly been a much larger collection if broken up into smaller pieces. In general, they don’t have the shorter atomicity of content suggested by some note takers. Goitein seems to have used his cards in a database-like fashion, similar to that expressed by Beatrice Webb [@Webb1926], though in his case his database method doesn’t appear to be as simplified or as atomic as hers. #

Card Index Output

As the ultimate goal of many note taking processes is to create some sort of output, as was certainly the case for Goitein’s work, let’s take a quick look at the result of his academic research career.

S.D. Goitein’s academic output stands at 737 titles based on a revised bibliography compiled by Robert Attal in 2000, which spans 93 pages. [@Attal2000] # # A compiled profile of Goitein lists 800 articles and reviews, 68 books, and 3 Festschriften which tracks with Robert Atta’s bibliography. #. Goitein’s biographer Hanan Harif also indicates a total bibliography of around 800 publications. [@NationalLibraryofIsrael2021] #. The careful observer will see that Attal’s list from 2000 doesn’t include the results of S.D. Goitein’s India book work which weren’t published in book form until 2007.

Perhaps foremost within his massive bibliography is his influential and magisterial six volume A Mediterranean Society: The Jewish communities of the Arab World as Portrayed in the Documents of the Cairo Geniza (1967–1993), a six volume series about aspects of Jewish life in the Middle Ages which is comprised of 2,388 pages. # When studying his card collection, one will notice that a large number of cards in the topically arranged or commonplace book-like portion were used in the production of this magnum opus. # Zinger says that they served as the skeleton of the series and indicates as an example:

 …in roll 26 we have the index cards for Mediterranean Society, chap. 3, B, 1, “Friendship” and “Informal Cooperation” (slides 375–99, drawer 24 [7D], 431–51), B, 2, “Partnership and Commenda” (slides 400–451, cards 452–83), and so forth. #

Given the rising popularity of the idea of using a zettelkasten (aka slip box or card index) as a personal knowledge management tool, some will certainly want to compare the size of Goitein’s output with that of his rough contemporary German sociologist Niklas Luhmann (1927-1990). Luhmann used his 90,000 slip zettelkasten collection to amass a prolific 550 articles and 50 books. [@Schmidt2016]. Given the disparity in the overall density of cards with respect to physical output between the two researchers one might suspect that a larger proportion of Goitein’s writing was not necessarily to be found within his card index, but the idiosyncrasies of each’s process will certainly be at play. More research on the direct correlation between their index cards and their writing output may reveal more detail about their direct research and writing processes.

Digital Archive

Following his death in February 1985, S.D. Goitein’s papers and materials, including his twenty-six drawer zettelkasten, were donated by his family to the Jewish National and University Library (now the National Library of Israel) in Jerusalem where they can still be accessed. [@Zinger2019] #

In an attempt to continue the work of Goitein’s Geniza lab, Mark R. Cohen and A. L. Udovitch made arrangements for copies of S.D. Goitein’s card index, transcriptions, and photocopies of fragments to be made and kept at Princeton before the originals were sent. This repository then became the kernel of the modern Princeton Geniza Lab. [@PrincetonGenizaLaba] # #

Continuing use as an active database and research resource

The original Princeton collection was compacted down to thirty rolls of microfilm from which digital copies in .pdf format have since been circulating among scholars of the documentary Geniza. [@Zinger2019] #

Goitein’s index cards provided a database not only for his own work, but for those who studied documentary Geniza after him. [@Zinger2019] # S.D. Goitein’s index cards have since been imaged and transcribed and added to the Princeton Geniza Lab as of May 2018. [@Zinger2019] Digital search and an index are also now available as a resource to researchers from anywhere in the word. #

Historically it has generally been the case that repositories of index cards like this have been left behind as “scrap heaps” which have meant little to researchers other than their originator. In Goitein’s case his repository has remained as a beating heart of the humanities-based lab he left behind after his death.

In Geniza studies the general rule of thumb has become to always consult the original of a document when referencing work by other scholars as new translations, understandings, context, history, and conditions regarding the original work of the scholar may have changed or have become better understood.[@Zinger2019] # In the case of the huge swaths of the Geniza that Goitein touched, one can not only reference the original fragments, but they can directly see Goitein’s notes, translations, and his published papers when attempting to rebuild the context and evolve translations.

Posthumous work

Similar to the pattern following Walter Benjamin’s death with The Arcades Project (1999) and Roland Barthes’ Mourning Diary (2010), Goitein’s card index and extant materials were rich enough for posthumous publications. Chief among these is India Traders of the Middle Ages: Documents from the Cairo Geniza “India Book.” (Brill, 2007) cowritten by Mordechai Friedman, who picked up the torch where Goitein left off. # # However, one must notice that the amount of additional work which was put into Goitein’s extant box of notes and the subsequent product was certainly done on a much grander scale than these two other efforts.

Notes per day comparison to other well-known practitioners

Given the idiosyncrasies of how individuals take their notes, the level of their atomicity, and a variety of other factors including areas of research, other technology available, slip size, handwriting size, etc. comparing people’s note taking output by cards per day can create false impressions and dramatically false equivalencies. This being said, the measure can be an interesting statistic when taken in combination with the totality of these other values. Sadly, the state of the art for these statistics on note taking corpora is woefully deficient, so a rough measure of notes per day will have to serve as an approximate temporary measure of what individuals’ historical practices looked like.

With these caveats firmly in mind, let’s take a look at Goitein’s output of roughly 27,000 cards over the span of a 35 year career: 27,000 cards / [35 years x 365 days/year] gives us a baseline of approximately 2.1 cards per day. #. Restructuring this baseline to single sided cards, as this has been the traditional advice and practice, if we presume that 3/4ths of his cards were double-sided we arrive at a new baseline of 3.7 cards per day.

Gotthard Deutch produced about 70,000 cards over the span of about 17 years giving him an output of about 11 cards per day. [@Lustig2019] #

Niklas Luhmann’s collection was approximately 90,000 cards kept over about 41 years giving him about 6 cards per day. [@Ahrens2017] #

Hans Blumenberg’s zettelkasten had 30,000 notes which he collected over 55 years averages out to 545 notes per year or roughly (presuming he worked every day) 1.5 notes per day. [@Kaube2013] #

Roland Barthes’ fichier boîte spanned about 37 years and at 12,250 cards means that he was producing on average 0.907 cards per day. [@Wilken2010] If we don’t include weekends, then he produced 1.27 cards per day on average. #

Finally, let’s recall again that it’s not how many thoughts one has, but their quality and even more importantly, what one does with them which matter in the long run. # Beyond this it’s interesting to see how influential they may be, how many they reach, and the impact they have on the world. There are so many variables hiding in this process that a fuller analysis of the statistical mechanics of thought with respect to note taking and its ultimate impact are beyond our present purpose.

Further Research

Based on a cursory search, no one seems to have picked up any deep research into Goitein’s card collection as a tool the way Johannes F.K. Schmidt has for Niklas Luhmann’s archive or the Jonathan Edwards Center at Yale has for Jonathan Edwards’ Miscellanies Index.

Goitein wrote My Life as a Scholar in 1970, which may have some methodological clues about his work and method with respect to his card index. He also left his diaries to the National Library of Israel as well and these may also have some additional clues. # Beyond this, it also stands to reason that the researchers who succeeded him, having seen the value of his card index, followed in his footsteps and created their own. What form and shape do those have? Did he specifically train researchers in his lab these same methods? Will Hanan Harif’s forthcoming comprehensive biography of Goitein have additional material and details about his research method which helped to make him so influential in the space of Geniza studies? Then there are hundreds of small details like how many of his cards were written on both sides? # Or how might we compare and contrast his note corpus to others of his time period? Did he, like Roland Barthes or Gotthard Deutch, use his card index for teaching in his earlier years or was it only begun later in his career?

Other potential directions might include the influence of Braudel’s lab and their research materials and methods on Goitein’s own. Surely Braudel would have had a zettelkasten or fichier boîte practice himself?



  1. In my preliminary literature search here, I have not found any direct references to indicate that Goitein specifically called his note collection a “Zettekasten”. References to it have remained restricted to English generally as a collection of index cards or a card index.↩︎
  2. While not directly confirmed (yet), due to the seeming correspondence of the number of cards and their corpus descriptions with respect to the sizes, it’s likely that the 20,000 3 x 5″ cards were his notes covering individual topics while the 7,000 5 x 8″ cards were his notes and descriptions of a single fragment from the Cairo Geniza. #↩︎

Santa’s Magnificent Zettelkasten: The Christmas Chronicles

Of course Santa Claus would have the most spectacular zettelkasten in the world!

He’s got billions of people and gifts for them to keep track of, so naturally he’s got a stupendous card index filing system to back it up! Usually Santa’s “List” gets the hero’s credit for his operation along with elves, reindeer, and a sleigh, but let’s be honest: he’s got a massive filing system that he uses to compile that naughty and nice list!

I appreciate that the movie The Christmas Chronicles (Netflix, 2018) features Santa’s main office in an extended sequence and shows off the backbone of his office operation. With centuries in operation and millions of moving parts, he’s obviously solved the logistics problem the way many before him have. His filing system seems to consist of alphabetically ordered names and letter correspondence he maintains with his juvenal suppliants. This system along with magic (presumably) allows him to make his famous list.

Throughout the movie Santa demonstrates his encyclopedic knowledge of people, their names, and long histories of what they’ve wanted for Christmas. Surely it was long and concerted work with his filing system which has made his work almost second nature, right?!?

The boxes pictured are definitely not standard library card catalog 3 x 5 inch size but are closer to a more classical 4 x 6 inch, or if you presume he’s using the DIN standard, which may be more likely, then A6 slips. If the shelves are roughly as deep as my own filing cabinet, then this room could easily contain roughly 13,925,000 slips. In comparison to Niklas Luhmann’s lifetime output of notes, this would represent roughly 155 Niklas Luhmanns—it’s no wonder that we call him Saint Niklas. 

Screen capture from the Christmas Chronicles featuring Santa Claus' dark wooden and cavernous office the back wall of which is covered in a massive card index file. In the foreground a young girl walks in to explore it.
Seen in this office photo are approximately 4,000 drawers of files! I totally want this office aesthetic.
Screen capture from the Christmas Chronicles featuring a girl staring in awe around Santa's office. In the background behind her is Santa's massive zettelkasten.
I suspect I would have the same awestruck look on my face when exposed to such a massive office infrastructure.

Screen capture from the Christmas Chronicles featuring a standing in awe at Santa's massive zettelkasten which fills the screen despite the wide angle shot. There are thousands upon thousands of drawers.

Screen capture from the Christmas Chronicles featuring a girl exploring Santa's zettelkasten wall using a steampunk style mechanized platform.
I thought I had a large filing cabinet for slips, but Santa needs a custom elevator platform just to reach his materials. This gives new meaning to Maschinen der Phantasie.

Screen capture from the Christmas Chronicles featuring a girl exploring Santa's zettelkasten. The close up shows here thumbing through an open drawer with a variety of colored filed letters. In the background we see a dozen drawers on the wall.

Screen capture from the Christmas Chronicles. The girl is closing the drawer she was exploring to look down into the office. There are hundreds of file drawers in the background behind her.

Screen capture from the Christmas Chronicles. A view into Santa's office which is suddenly populated with several dozen incredibly cute elves.
Naturally if one had such a large zettelkasten, one would want their own army of magical elves with nimble fingers to help manage it all!

Thoughts on Zettelkasten numbering systems

I’ve seen variations of the beginner Zettelkasten question:

“What happens when you want to add a new note between notes 1/1 and 1/1a?”

asked at least a dozen times in the Reddit fora related to zettelkasten and note taking, on, or in other places across the web.

Dense Sets

From a mathematical perspective, these numbering or alpha-numeric systems are, by both intent and design, underpinned by the mathematical idea of dense sets. In the areas of topology and real analysis, one considers a set dense when one can choose a point as close as one likes to any other point. For both library cataloging systems and numbering schemes for ideas in Zettelkasten this means that you can always juxtapose one topic or idea in between any other two.

Part of the beauty of Melvil Dewey’s original Dewey Decimal System is that regardless of how many new topics and subtopics one wants to add to their system, one can always fit another new topic between existing ones ad infinitum.

Going back to the motivating question above, the equivalent question mathematically is “what number is between 0.11 and 0.111?” (Here we’ve converted the artificial “number” “a” to a 1 and removed the punctuation, which doesn’t create any issues and may help clarify the orderings a bit.) The answer is that there is an infinite number of numbers between these!

This is much more explicit by writing these numbers as:

Naturally 0.1101 is between them (along with an infinity of others), so one could start here as a means of inserting ideas this way if they liked. One either needs to count up sequentially (0, 1, 2, 3, …) or add additional place values.

Decimal numbering systems in practice

The problem most people face is that they’re not thinking of these numbers as decimals, but as natural numbers or integers (or broadly numbers without any decimal portions). Though of course in the realm of real numbers, numbers above 0 are dense as well, but require the use of their decimal portions to remain so.

The tough question is: what sorts of semantic meanings one might attach to their adding of additional place values or their alphabetical characters? This meaning can vary from person to person and system to system, so I won’t delve into it here.

One may find it useful to logically chunk these numbers into groups of three as is often done using commas, periods, slashes, dashes, spaces, or other punctuation. This doesn’t need to mean anything in particular, but may help to make one’s numbers more easily readable as well as usable for filing new ideas. Sometimes these indicators can be confusing in discussion, so if ever in doubt, simply remove them and the general principles mentioned here should still hold.

Depending on one’s note taking system, however, when putting cards into some semblance of a logical, sort-able order (perhaps within a folder for example), the system may choke on additional characters beyond the standard period to designate a decimal number. For example: within Obsidian, if you have a “zettelkasten” folder with lots of numbered and named files within it, you’ll want to give each number the maximum number of decimal places so that when doing an alphabetic sort within the folder, all of the numbered ideas are properly sorted. As an example if you give one file the name “0.510 Mathematics”, another “0.514 Topology” and a third “0.5141 Dense Sets” they may not sort properly unless you give the first two decimal expansions to the ten-thousands place at a minimum. If you changed them to “0.5100 Mathematics” and “0.5140 Topology, then you’re in good shape and the folder will alphabetically sort as you’d expect. Similarly some systems may or may not do well with including alphabetic characters mixed in with numbers.

If using chunked groups of three numbers, one might consider using the number 0.110.001 as the next level of idea between them and then continuing from there. This may help to spread some of the ideas out as surely one may have yet another idea to wedge in between 0.110.000 and 0.110.001?

One can naturally choose almost any any (decimal) number, so long as it is somewhat “near” the original behind which one places it. By going out further in the decimal expansion, one can always place any idea between two others and know that there will be a number that it can be given that will “work”.

Generally within numbers as we use them for mathematics, 0.100000001 is technically “closer” by distance measurement to 0.1 than 0.11, (and by quite a bit!), but somehow when using numbers for zettelkasten purposes, we tend to want to not consider them as decimals, as the Dewey Decimal System does. We also have the tendency to want to keep our numbers as short as possible when writing, so it seems more “natural” to follow 0.11 with 0.111, as it seems like we’re “counting up” rather than “counting down”.

Another subtlety that one sees in numbering systems is the proper or improper use of the whole numbers in front of the decimal portions. For example, in Niklas Luhmann’s system, he has a section of cards that start with 3.XXXX which are close to a section numbered 35.YYYY. This may seem a bit confusing, but he’s doing a bit of mental gymnastics to artificially keep his numbers smaller. What he really means is 3000.XXXX and 3500.YYYY respectively, he’s just truncating the extra zeros. Alternately in a fully “decimal system” one would write these as 0.3000.XXXX and 0.3500.YYYY, where we’ve added additional periods to the numbers to make them easier to read. Using our original example in an analog system, the user may have been using foreshortened indicators for their system and by writing 1/1a, they may have really meant something of the form 001.001/00a, but were making the number shorter in a logical manner (at least to them).

The close observer may have seen Scott Scheper adopt the slightly longer numbers in the thousands (like 3500.YYYY) as a means of remedying some of the numbering confusion many have when looking at Luhmann’s system.

Those who build their systems on top of existing ones like the Dewey Decimal Classification, or the Universal Decimal Classification may wish to keep those broad categories with three to four decimal places at the start and then add their own idea number underneath those levels.

As an example, we can use the numbering for Finsler geometry from the Dewey Decimal Classification wikipedia page shown as:

500 Natural sciences and mathematics
   510 Mathematics
      516 Geometry
         516.3 Analytic geometries
            516.37 Metric differential geometries
               516.375 Finsler geometry

So in our zettelkasten, we might add our first card on the topic of Finsler geometry as “516.375.001 Definition of Finsler geometry” and continue from there with some interesting theorems and proofs on those topics.

Don’t Waste Time on Complex Classification Systems

Of course, while this is something one can do doesn’t mean that one should do it. Going too far down the rabbit holes of “official” forms of classification this way can be a massive time wasting exercise as in most private systems, you’re never going to be comparing your individual ideas with the private zettelkasten of others and in practice the sort of standardizing work for classification this way is utterly useless. Beyond this, most personal zettelkasten are unique and idiosyncratic to the user, so for example, my math section labeled 510 may have a lot more overlap with history, anthropology, and sociology hiding within it compared with others who may have all of their mathematics hiding amidst their social sciences section starting with the number 300. One of the benefits of Luhmann’s ad hoc numbering scheme, at least for him, is that it allowed his system to be much more interdisciplinary than using a more complicated Dewey Decimal oriented system which may have dictated moving some of his systems theory work out of his politics area where it may have made more sense to him in addition to being more productive on a personal level.

Of course if you’re using the older sort of commonplacing zettelkasten system that was widely in use before Luhmann’s variation, then perhaps using a Dewey-based system may be helpful to you?

A Touch of History

As both a mathematician working in the early days of real analysis and a librarian, I wouldn’t be surprised if some of these loose ideas may have occurred tangentially to Gottfried Wilhelm Leibniz (1646 – 1716), though I’m currently unaware of any specific instances within his work. One must note, however, that some of the earliest work within library card catalogs as we know and use them today stemmed from 1770s Austria where governmental conscription needs overlapped with card cataloging systems (Krajewski, 2011). It’s here that the beginnings of these sorts of numbering systems begin to come into use well before Melvil Dewey’s later work which became much more broadly adopted.

The German “file number” (aktenzeichen) is a unique identification of a file, commonly used in their court system and predecessors as well as file numbers in public administration since at least 1934. We know Niklas Luhmann studied law at the University of Freiburg from 1946 to 1949, when he obtained a law degree, before beginning a career in Lüneburg’s public administration where he stayed in civil service until 1962. Given this fact, it’s very likely that Luhmann had in-depth experience with these sorts of file numbers as location identifiers for files and documents. As a result it’s reasonably likely that a simplified version of these were at least part of the inspiration for his own numbering system. [] []

Your own practice

At the end of the day, the numbering system you choose needs to work for you within the system you’re using (analog, digital, other). I would generally recommend against using someone else’s numbering system unless it completely makes sense to you and you’re able to quickly and simply add cards to your system with out the extra work and cognitive dissonance about what number you should give it. The more you simplify these small things, the easier and happier you’ll be with your set up in the end.


Krajewski, Markus. Paper Machines: About Cards & Catalogs, 1548-1929. Translated by Peter Krapp. History and Foundations of Information Science. MIT Press, 2011.

Munkres, James R. Topology. 2nd ed. 1975. Reprint, Prentice-Hall, Inc., 1999.

Featured photo by Manson Yim on Unsplash

NaNoWriMo with Zettelkasten Approach for an AcWriMo Non-Fiction Writing

Using Niklas Luhmann’s rough average of six zettels per day working full time for 8 hours a day versus writing approximately 1,667 words in an hour’s work (~28 words written per minute, which seems a reasonable average), I’ve created a zettelkasten word count equivalent for reading, research, and note making.

  • 28 words for every minute spent reading and making fleeting notes.
  • 415 words for every well-formed, fully written out permanent note
  • 500 words for every well-formed, fully written out and installed permanent note (includes work to install it in the box)
  • 84 words for every cross link created from one note to another
  • 140 words for every bibliographic card created
  • 56 words for every index entry created

If you’re diligently working at any or all of the above, instead of measuring all the small pieces, you could just use a 28 word/minute measure for your zettelkasten-based work.

If you’re not a full time research-only academic (without a teaching load or other administrative obligations) and for fun want to measure your NaNoWriMo for non-fiction work on a card per day basis using Niklas Luhmann as a guide/measure, then you should do the reading, research and note taking work to produce 0.75 cards per day (that is, well written permanent notes installed, indexed, and well-linked; we’re not keeping track of the indexing cards, bibliographic cards, or other fleeting notes here, which you’ll also be doing along the way) to keep pace for an equivalent 50,000 words during the month. This is about 5.25 cards per week or about 23 cards for the entire month.

The goal here is, instead of churning out raw words, to churn out reading, research, and note making towards material you can reasonably use to write journal articles, book chapters, or a full non-fiction book.

If you’re using an index card-based system for fiction writing the way Vladimir Nabokov did, then you really should do a traditional word count as that’s more closely in line with the workflow of the standard NaNoWriMo work.

N.B. This probably overshoots the mark, as the 6 cards/day number for Luhmann probably includes all cards and not just permanent notes in his entire collection over his entire lifetime’s work. It also doesn’t take into account the possibility that he carried a teaching load, administrative work, fundraising work, or other nonsense required of professors.) Of course this is is all just for fun anyway, so… quit worrying and start researching and writing a little bit every day.

Bookmarked ‘Mere chips from his workshop’: Gotthard Deutsch’s monumental card index of Jewish history by Jason Lustig (History of the Human Sciences | Sage Journals)
Gotthard Deutsch (1859–1921) taught at Hebrew Union College in Cincinnati from 1891 until his death, where he produced a card index of 70,000 ‘facts’ of Jewish history. This article explores the biography of this artefact of research and poses the following question: Does Deutsch’s index constitute a great unwritten work of history, as some have claimed, or are the cards ultimately useless ‘chips from his workshop’? It may seem a curious relic of positivistic history, but closer examination allows us to interrogate the materiality of scholarly labor. The catalogue constitutes a total archive and highlights memory’s multiple registers, as both a prosthesis for personal recall and a symbol of a ‘human encyclopedia’. The article argues that this mostly forgotten scholar’s work had surprising repercussions: Deutsch’s student Jacob Rader Marcus (1896–1995) brought his teacher’s emphasis on facticity to the field of American Jewish history that he pioneered, catapulting a 19th-century positivism to the threshold of the 21st century. Deutsch’s index was at an inflection point of knowledge production, created as historians were shifting away from ‘facts’ but just before new technologies (also based on cards) enabled ‘big data’ on a larger scale. The article thus excavates a vision of monumentality but proposes we look past these objects as monuments to ‘heroic’ scholarship. Indeed, Deutsch’s index is massive but middling, especially when placed alongside those of Niklas Luhmann, Paul Otlet, or Gershom Scholem. It thus presents a necessary corrective to anointing such indexes as predecessors to the Internet and big data because we must keep their problematic positivism in perspective.
In honor of Yom Kippur today, I’m celebrating with acknowledgement of Gotthard Deutsch’s “monumental card index [zettelkasten] of Jewish history”. I hope everyone had an easy fast.

Zettelkasten Method State of the Art in 1898

Many people mistakenly credit Niklas Luhmann with the invention of the zettelkasten method, so I’ve been delving into historical note taking practices. I’ve recently come across a well known and influential book on historical method from the late 1800s that has well described version of the slip (box) method.

Originally published in French in 1897 as Introduction aux études historiques and then translated into English by George Godfrey Berry, Henry Holt and Company published Introduction to the Study of History in 1898 by authors Charles Victor Langlois and Charles Seignobos. Along with Ernst Bernheim’s popular Lehrbuch der historischen Methode mit Nachweis der wichtigsten Quellen und Hülfsmittelzum Studium der Geschichte (Leipzig: Duncker & Humblot, 1889), Langlois and Seignobos’ text is one of the first comprehensive manuals discussing the use of scientific techniques in historical research.

Primarily written by Seignobos, Book II, Chapter IV “Critical Classification of Sources” has several sections on the zettelkasten method under the section headings:

  • Importance of classification—The first impulse wrong—Thenote-book system not the best—Nor the ledger-system—Nor the “system” of trusting the memory
  • The system of slips the best—Its drawbacks—Means ofobviating them—The advantage of good “private librarian-ship”

This section describes a slip method for taking notes which is ostensibly a commonplace book method done using slips of paper (fiches in the original French) instead  of notebooks. Their method undergirds portions of the historical method they lay out in the remainder of the book. Seignobos calls the notebook method “utterly wrong” and indicates that similar methods have been “universally condemned” by librarians as a means of storing and maintaining knowledge. Entertainingly he calls the idea of attempting to remember one’s knowledge using pure memory a “barbarous method”. 

The slip method is so ubiquitous by the time of his writing in 1897 that he says “Every one admits nowadays that it is advisable to collect materials on separate cards or slips of paper.”

The Slip Method

The book broadly outlines the note taking process: 

The notes from each document are entered upon a loose leaf furnished with the precisest possible indications of origin. The advantages of this artifice are obvious : the detachability of the slips enables us to group them at will in a host of different combinations ; if necessary, to change their places : it is easy to bring texts of the same kind together, and to incorporate additions, as they are acquired, in the interior of the groups to which they belong. As for documents which are interesting from several points of view, and which ought to appear in several groups, it is sufficient to enter them several times over on different slips ; or they may be represented, as often as may be required, on reference-slips.

Seignobos further advises, as was generally common, “to use slips of uniform size and tough material” though he subtly added the management and productivity advice “to arrange them at the earliest opportunity in covers or drawers or otherwise.”

In terms of the form of notes, he says

But it will always be well to cultivate the mechanical habits of which professional compilers have learnt the value by experience: to write at the head of every slip its date, if there is occasion for it, and a heading in any case; to multiply cross-references and indices; to keep a record, on a separate set of slips, of all the sources utilised, in order to avoid the danger of having to work a second time through materials already dealt with.

Where the Luhmann fans will see a major diversion for the system compared to his internal branching system is in its organization. They describe a handful of potential organizations based on the types of notes and their potential uses, though many of these use cases specific to historical research are now better effected by databases and spreadsheets. As for the broader classes of more traditional literature-based textual notes, they recommend grouping the slips in alphabetical order of the words chosen as subject headings. Here, even in a French text translated to English, the German word Schlagwörter is used. It can be translated as “headwords”, “catchwords” or “topical headings” though modern note takers, particularly in digital contexts, may be more comfortable with the translation “tags”.

While there are descriptions of cross-linking or cross-referencing cards from one to another, there is no use of alpha-numeric identifiers or direct juxtaposition of ideas on cards as was practiced by Luhmann.

The authors specifically credit Ernst Bernheim’s Lehrbuch der historischen Methode several times in the book. While a lot of the credit is geared toward their broader topic of historical method, Bernheim provides a description of note taking very similar to their method. I’ve found several copies of Bernheim’s text in German, but have yet to find any English translations. 

Both Bernheim and Langlois/Seignobos’ work were influential enough in the areas of history specifically and the humanities in general that Beatrice Webb (an influential English sociologist, economist, socialist, labour historian, and social reformer who was a co-founder of the London School of Economics, the Fabian Society, and The New Statesman) cites their work in Appendix C “The Art of Note-Taking” in her 1926 autobiographical work My Apprenticeship, which was incredibly popular and went through multiple reprintings in the nearly full century since its issue. Her personal use of this note taking method would appear to pre-date both books (certainly the Langlois/Seignobos text), however, attesting to its ubiquity in the late 1800s.

What is the “true” zettelkasten method?

Scott Scheper has recently written that personal communication with Luhmann’s youngest son Clemmens Luhmann indicated that Luhmann learned his method in 1951 from the Johannes Erich Heyde text Technik des wissenschaftlichen Arbeitens (with several German editions from 1931 onward). This book’s note taking method is broadly similar to that of the long held commonplace book maintained on index cards as seen in both Langlois/Seignobos (1897) and Webb (1926). One of the few major differences in Heyde was the suggestion to actively make and file multiple copies of the same card under different topical headings potentially using carbon copy paper to speed up the process. While it’s possible that Luhmann may have either learned the modifications of his particular system from someone or modified it himself, it is reasonably obvious that there is a much longer standing tradition as early as Konrad Gessner in 1548 to the middle of the 20th century of a zettelkasten tradition that is more similar to the commonplace book tradition effectuated with index cards (or slips “of a similar size”). Luhmann’s system, while seemingly more popular and talked about since roughly 2013, is by far the exception rather than the rule within the broader history of the “zettelkasten method”. With these facts in mind, we should be talking about a simpler, historical zettelkasten method and a separate, more complex/emergent Luhmann method.

Call for Model Examples of Zettelkasten Output Processes

Perhaps too much of the resurgence of the zettelkasten idea and the online space about it is focused on what a zettelkasten is or how it should be done. After this, descriptions of the process of collecting material for one’s zettelkasten is followed by using it to generate new ideas and thought, though this last part is relatively sparce in comparison. Very little of the discussion or examples I’ve seen in online fora, social media, websites, and the blogosphere is focused on actively using them for creating actual long form output.

As Luhmann’s (all-too-frequently used) example is so powerful, I think it would be massively helpful if users had stronger examples of what these explicit creation workflows looked like, particularly at the longer end of creation of chapters or even book length spaces. Are there any detailed posts, videos, other media about how one approached this problem? What worked well? What didn’t? What would you do differently next time? Have you done this multiple times and now settled into something you feel is most efficient? Is your process manual/digital? What tools helped along the way for laying out and doing the actual stitching together and editing? Would you use them again or try something else? Have you experimented with different methods or practices?

Here, I’m looking for direct and actual experience; I’m explicitly not looking for “this is how I would do it” responses.

Because it’s much easier and far more successful for humans to imitate the practice of others than to innovate it for themselves, I’m ultimately looking not for outlines of what people recommend, but public examples of the practices in progress. Who can show their actual “receipts” and in a reasonably linear and practical way for others to follow? We suffer from a lack of these practices being visible online as most aren’t. Further even the digital ones aren’t public, or if they are, they aren’t well known.

As an example of the broader problem, I’ve yet to see a week go by that someone doesn’t read Ahrens’ generally excellent book, but in posting online they still seem lost in attempting to put the lowest level ideas into active practice.

Personally, I use as a digital tool for the majority of my note taking. One could follow my feed and see it in real time if they choose. There are benefits for this public practice and I’m aware that many people follow this feed of notes out of curiosity. I’ve even gotten emails from folks indicating that they’ve learned some interesting things for use in their own practices. Sadly, the follow up of revision, cross linking, active indexing, and subsequent growth isn’t public (yet), though the platform I’m using is open to active public conversation and commentary, which is a useful side benefit. I have seen a few other public examples of others’ practices, some in video form, though this can be dull as the time and effort is work and doesn’t make for powerful entertainment because it isn’t. Still these public examples can be far more powerful than some of the explanations I’ve seen, especially for beginners who don’t comprehend the long term benefits (surprise, serendipity, insight, emergent creativity) and who generally focus on the minutiae for lack of direct experience.

On the creation portion, I’m currently experimenting with carrying out the original  instructions of Konrad Gessner, an early zettelmacher, as laid out in his book Pandectarum sive Partitionum Universalium. (1548. Zurich: Christoph Froschauer) and hope to report back shortly about the experience. 

Call for explicit examples

So where are the examples? Show us your receipts. Who’s doing this in public that people can follow? Who can be imitated until people have the experience(s) to do this more easily on their own? Let’s collect some of the best (or at least extant) examples for sharing with others. 

Once we’ve got some concrete examples then we can study them and iterate on them.

Too many people seem intent on potentially wasting their time by innovating on a practice they haven’t even tried because someone in the productivity space (who usually hasn’t tried it either) wrote a page long post saying it would be a good idea. I know we can do far better.

Replied to a thread by Scott P. Scheper and Alexandra Graßler (Twitter)
I’ll go you one better with the likely historical precedent for Niklas Luhmann’s zettelkasten numbering system: conscription numbers on Viennese houses in 1770s!

Alberto Cevolini & Markus Krajewski have relevant research. There are still a few missing puzzle pieces however.

Tiago, I’ve started into an advanced copy of your forthcoming book and at the end of the introduction you have a footnote:

Other popular terms for such a system include Zettelkasten (meaning “slipbox” in German, coined by influential sociologist Niklas Luhmann), Memex (a word invented by American inventor Vannevar Bush), and digital garden (named by popular online creator Anne-Laure Le Cunff)

Please know that the zettelkasten and its traditions existed prior to Niklas Luhmann. He neither invented them nor coined their name. It’s a commonly repeated myth on the internet that he did and there’s ample evidence of their extensive use prior to his well known example. I’ve documented some brief history on Wikipedia to this effect should you need it:

The earliest concept of a digital garden stems from Mark Bernstein’s essay Hypertext Gardens: Delightful Vistas in 1998. This torch was picked up by academic Mike Caulfield in a 2015 keynote/article The Garden and The Stream: A Technopastoral.

Anne-Laure Le Cunff’s first mention of “digital garden” was on April 21, 2020

Which occurred just after Maggie Appleton’s mention on 2020-04-15

And several days after Justin Tadlock’s article on 2020-04-17 

Before this there was Joel Hooks by at least 2020-02-04 , though he had been thinking about it in late 2019.

He was predated by Tom Critchlow on 2018-10-18 who credits Mike Caulfield’s article from 2015-10-17 as an influence. has versions of the phrase going back into the early 2000’s:*/%22digital%20garden%22

Hopefully you’re able to make the edits prior to publication, or at least in an available errata.

For those who’ve been waiting for it to show up, the digitized version of box 9 of Niklas Luhmann’s second zettelkasten is now available online. It contains many of his notes on the zettelkasten itself.