Zettelkasten - Term and Definition

Andy · May 2025

The different users in your use-case model remind me of Doron Mayer's "inner workflow team" (Wayback Machine link) that I mentioned previously, where the different users are different roles that we play in a creative workflow. In other words, the creative professional, student, and project manager in your diagram are not necessarily different people!

Edmund · May 2025

@Andy: Thank you for sharing this link. It's a good overview. Yes, the model uses roles. One person may have different roles when using Zettelkasten. Not every role needs all use cases.

Edmund · May 2025

A Zettelkasten can be defined within it's generalisation-specialisation structure (A is a B) and it's whole-part structure (A is part of B). Here's a new Zettelkasten model:

Zettelkasten - An Object-Oriented Model.

Zoom in and you can see the differences in detail:

We may use it to compare different classes and objects like a Zettelkasten and a Personal Wiki.

In this example the model shows:

A "Personal Wiki" can be defined as component of a "Personal Knowledge Management System" which can be a "Zettelkasten", a Digital Garden, the PARA Method and many others .

More about: Reddit

ctietze · May 2025

@Edmund Category theory diagram next, please

Edmund · May 2025

@ctietze said:
@Edmund Category theory diagram next, please

Great idea. 👍

But here is the answer from my Zettelkasten:

I’m Not Young Enough To Know Everything.
— Oscar Wilde

😉

Edmund · May 2025

A Zettelkasten is a personal knowledge management system.

What is the minimum set of atomic notes required to explain a Zettelkasten? - I'd say it's 48. What's your number?

Here's my start with seven initial notes:

One restrictive rule: Only use notes from your existing Zettelkasten.

Edmund · May 2025

A Zettelkasten Metaphorical Model.

In this model we understand Zettelkasten through the use of metaphors and analogies. Changing the metaphor changes the way we think. I started my Zettelkasten using Luhmann's metaphor: "A Zettelkasten is a communication partner."

Today, however, I see the Zettelkasten community as my preferred communication partner. Why not change the metaphor? My latest idea: My Zettelkasten is a gym for my brain. Let's see what happens.

Also see: https://forum.zettelkasten.de/discussion/comment/23036/#Comment_23036

Andy · May 2025

@Edmund said:

In this model we understand Zettelkasten through the use of metaphors and analogies. Changing the metaphor changes the way we think. I started my Zettelkasten using Luhmann's metaphor: "A Zettelkasten is a communication partner."

Today, however, I see the Zettelkasten community as my preferred communication partner. Why not change the metaphor? My latest idea: My Zettelkasten is a gym for my brain. Let's see what happens.

Here's an obligatory link to an earlier discussion that @Edmund started: "What is your preferred metaphor for Zettelkasten? And why?" (April 2022)

Tiago Forte's blog post "What do you call your second brain?" (August 2022) has some good ones too, but it's worth noting that they tend to be mind/head/brain-centered.

The gym metaphor may be more likely to lead you in a new direction if you omit the "for my brain" part, because that part makes it very similar to all the other mind/head/brain-centered metaphors, whereas if you think of it more broadly as relating to the whole body like a physical gym, then the gym metaphor could reveal something new that the other metaphors lack, perhaps.

EDIT: For example, if I call my Zettelkasten a "gym for my heart", it has different conceptual associations than "gym for my brain", and could lead to different emphases and outcomes. In terms of the MBTI model that you posted earlier in this discussion, the brain-versus-heart distinction is T versus F. Perhaps it's no surprise that someone who scores as "INFJ" (me) would point out the F alternative, as much as I aspire to apply my T skills in knowledge work.

Andy · May 2025

After further consideration, I admit that calling a Zettelkasten a "gym for my heart" may sound quite ridiculous. But I submit for consideration that calling it a "gym for my brain" is equally as ridiculous, given the first lesson in Lisa Feldman Barrett's book Seven and a Half Lessons About the Brain (2020): "Your brain is not for thinking."

Edmund · May 2025

@Andy said:
Here's an obligatory link to an earlier discussion that @Edmund started: "What is your preferred metaphor for Zettelkasten? And why?" (April 2022)

Thank you for reminding me at our amazing metaphor discussion three years ago.

Tiago Forte's blog post "What do you call your second brain?" (August 2022) has some good ones too, but it's worth noting that they tend to be mind/head/brain-centered.

Great link. :-)

The gym metaphor may be more likely to lead you in a new direction if you omit the "for my brain" part, because that part makes it very similar to all the other mind/head/brain-centered metaphors, whereas if you think of it more broadly as relating to the whole body like a physical gym, then the gym metaphor could reveal something new that the other metaphors lack, perhaps.

I started with the gym metaphor as an "experiment". The experience I've gained at a physical gym can easily be transferred to a mental one. However, I have no idea where this will lead.

What I learned from the metaphors in the model above:

It can be used for analysis. Why did Luhmann publish the "communication partner" metaphor? What's his personality type?
It can be used for goal setting as a metaphor for a north star goal, a long-term, aspirational goal that serves as a guiding principle providing a clear direction and focus. It's more than a specific target; it's the overarching vision that motivates and inspires, guiding daily decisions and actions.
It can be used for experiments.

Here is an updated version of the Zettelkasten Metaphorical Model:

We see that metaphors are double-edged: they reveal by mapping one domain onto another—but they also obscure by ignoring what doesn't fit the mapping.

Edmund · May 2025

@Andy said:
But I submit for consideration that calling it a "gym for my brain" is equally as ridiculous

Yes, it is. For me, though, it's part of a mental experiment. There's no fact behind it. There's no deeper meaning. But it's a chance to produce new insights. A tool to enable creativity.

Edmund · May 2025

Zettelkasten - A Mental Training Model

The model is based on the metaphor "Zettelkasten is a gym for my brain". Here are some of the exercises I use to improve serendipitous discovery in my Zettelkasten:

mrcmrc · May 2025

Edmund, as always your diagrams are splendid and very interesting. I was wondering: are they part of an ebook you have yet to publish?

Edmund · May 2025

@mrcmrc said:
Edmund, as always your diagrams are splendid and very interesting. I was wondering: are they part of an ebook you have yet to publish?

I'm sure they will be included in the book. But not all of them. Only the best ones.

Nick · June 2025

@Edmund said:
12 Zettelkasten Models

Why use a few simple words to define the term Zettelkasten, when it can be explained just as well with a dozen sophisticated models. 😼

I have a note dedicated to collecting analogies for a zettelkasten, these are the ones I have so far:

Zettelkasten as a Web of Reality
Zettelkasten as a Box of Legos
Zettelkasten as Knowledge Exploration
Zettelkasten as an Abstraction Machine
Zettelkasten as an Academic Idea Tracker
Zettelkasten as Plant Breeding
Zettelkasten as a Reference Tracker
Zettelkasten as Learning Machine
Zettelkasten as Fieldstone Wall

Edmund · June 2025

@Nick said:
I have a note dedicated to collecting analogies for a zettelkasten, these are the ones I have so far:

Zettelkasten as a Web of Reality

Zettelkasten as a Box of Legos

Zettelkasten as Knowledge Exploration

Zettelkasten as an Abstraction Machine

Zettelkasten as an Academic Idea Tracker

Zettelkasten as Plant Breeding

Zettelkasten as a Reference Tracker

Zettelkasten as Learning Machine

Zettelkasten as Fieldstone Wall

What's your favorite?

I'm still active with my "Mental Gym Model":

Here is a first prototype for printing on cards:

Edmund · July 2025

We are still having an ongoing discussion about the definition of Zettelkasten: https://forum.zettelkasten.de/discussion/3286/my-current-definition-of-the-zettelkasten-method

I believe that there is no such thing as a perfect definition. Setting a proficiency level for Zettelkasten, like CIFRZ, may help to find a definition that might be useful for the related users:

However, we need to consult our users as started by @Sascha . And we need to ask users at different levels.

Edmund · August 7

The Minimalist's Zettelkasten Definition

See also:

What's A "Zettlekasten" (Oh, no, not again!)?

Edmund · September 4

Zettelkasten Ecosystem Model

According to the Merriam-Webster Dictionary, an ecosystem is a system made up of an ecological community of living things interacting with their environment, especially under natural conditions.

I think tool and method in a Zettelkasten are less like software and workflow, and more like two organisms in a symbiotic relationship. Seeing Zettelkasten tools and methods as “living things” leads to a concept map with major interactions as named connections:

The related view: A Zettelkasten is a thinking ecosystem in which a method and a medium continuously shape each other.

For me an interesting question now is:

How does the tool change the method—and how does the method change what the tool becomes?

andang76 · September 4

I find the same questions involving the author even more interesting :-)

In my practice I've seen relevant long term effects to my mind, besides the well know dynamics such conversational effects between zettels and author and reactivations of ideas into the brain from zettels.

I've seen my mind changed by zettelkasten.

ZettelDistraction · September 5

Whenever I read "ecosystem" for "digital system," I want to know who the top and bottom feeders are.

harr · September 5

I have to think of stories where the author appear in the story. What do the "tool" and the "method" think about the "person"? Do they perceive the human as a god-like force that can create and destroy their ecosystem at will? And what happens, when a "person" leaves their zettelkasten for good? Are "tool" and "method" still alive?

ZettelDistraction · September 5

@harr said:
I have to think of stories where the author appear in the story.

Speaking of narratives in which the author appears in the story, there is the divine narrative:

To believe in God is thus to experience the world as a divine narration existing from, and unfolding in conformity with, the point of view of a creator and narrator.

Believing in the existence of God is not having an ontology in which are listed all the galaxies and nebulae and stars, and planets, and frogs, and pine trees and Lithuanians and also God. That is just silly. Believing in God is experiencing the world as a divine story in which I am a character.

Why am I an atheist? Because I do not, cannot, experience the world in that way.

-- Robert Paul Wolff (1933-2025). IN DEFENSE OF ATHEISM, IN A MANNER OF SPEAKING.

Edmund · September 6

@andang76 said:
In my practice I've seen relevant long term effects to my mind, besides the well know dynamics such conversational effects between zettels and author and reactivations of ideas into the brain from Zettels.
I've seen my mind changed by zettelkasten.

That's what I've noticed, too.

And I got one new entry to my list of open questions: “How does Zettelkasten change my thinking?”

It’s directly related to: “How does AI change my thinking?”

ZettelDistraction · September 7

@ZettelDistraction said:
...

-- Robert Paul Wolff (1933-2025). IN DEFENSE OF ATHEISM, IN A MANNER OF SPEAKING.

Apologies for this. While the definition seems right I'm not endorsing the conclusion. My Bayesian prior assigns 50% odds.

harr · September 8

@ZettelDistraction said:
Apologies for this. While the definition seems right I'm not endorsing the conclusion. My Bayesian prior assigns 50% odds.

I think the text works well, even if one doesn't share the conclusion, because it's not really a defense of atheism. The author describes belief in God as an experience: "Believing in God is experiencing the world as a divine story in which I am a character."

I don't think that the absence of that experience proves the absence of God. Neither does the presence of the experience prove God's existence. Yet the experience matters, when people talk about their beliefs. Believers tend to experience God as a force that guides their lives.

I'm wondering if entities like a "tool" or a "method" can have such experiences. :-)

Edmund · September 20

Zettelkasten family resemblance: Exploring visual similarities in basic models.

In evolutionary biology, family resemblance describes how groups of organisms or genes share overlapping similarities through common ancestry and intermediate relatives without needing a single, universal defining feature. We have already discussed the concept of shared traits in an attempt to improve our understanding of Zettelkasten without strict rules:

Zettelkasten is not one thing with fixed boundaries. It's a family of approaches that resemble each other through purpose, structure, and function. You don't need all the traits—you need enough to belong. — Based on: Zettelkasten - Term and Definition — Zettelkasten Forum

and:

In Zettelkasten and personal knowledge management discourse, Zettelkasten functions as a family-resemblance category organized around central exemplars. — Based on: Zettelkasten as a Family Resemblance Category · flengyel/Zettel Wiki · GitHub by @ZettelDistraction

One of our first attempts to identify structural similarities between our various Zettelkasten approaches using visual representations can be found here: What is going on in a Zettelkasten visually by @Annabella . Now let's have a second one. As you know, I love visual representations. So, my question is: can the similarities between different Zettelkasten models be illustrated visually?

1. Luhmann's Zettelkasten
Let us start with my basic model of Luhmann's analog Zettelkasten system. It consists of two slip-boxes, a main slip-box and a bibliographical slip-box, each of which is focused on different types of notes. All in all, I've found five types of notes in the shown reference.

As we know, Luhmann's Zettel form the core of the Zettelkasten system. Three types of structure notes are added here to enable an easy access.

2. Ahrens' Zettelkasten
The famous "Smart Notes" system based on the initial Zettelkasten from Luhmann:

The core is the same, but two types of notes are added: Fleeting Notes and Project Notes. Both are analog notes. Fleeting Notes are written with pen on paper, Project Notes are kept in physical binders. The digital notes are kept in two specialized digital systems. Literature Notes are placed in a reference system such as Zotero, while Permanent Notes and three others are kept in tools such as Roam Research or Obsidian.

3. Minimalist's Zettelkasten
There is only one digital toolset. Tools like Obsidian allow you to keep all notes in one place. Each of the five types of notes has its own folder for organization. Unlike Luhmann and Ahrens, Structure Notes are placed in a separate folder. The five types of notes have subtypes. These are indicated by an appropriate tagging system.

Final
In genetics, we inherit DNA from both parents. This determines physical characteristics such as bone structure, eye colour, nose shape and freckles. In the Zettelkasten ecosystem we inherit from two parents as well: the method and the tool. See also: Zettelkasten - Term and Definition - Page 2 — Zettelkasten Forum

harr · September 20

@Edmund said:
1. Luhmann's Zettelkasten
Let us start with my basic model of Luhmann's analog Zettelkasten system. It consists of two slip-boxes, a main slip-box and a bibliographical slip-box, each of which is focused on different types of notes. All in all, I've found five types of notes in the shown reference.

After I had a closer look at the digitized version of Luhmann's ZK, I'd group and count the types somewhat differently.

Zettelkasten can refer to the entirety of several physical wooden objects containing drawers and paper slips. The content of the drawers can be divided into the old Zettelkasten I and and the later Zettelkasten II. There's also a separation between the main zettels and the bibliographic apparatus. But there's also another section with miscalleneous note types.

For the purpose of a "basic model", I'd ignore the sections and go straight for note types. I don't think it matters much where they are stored in the wooden boxes. I consider only three note types essential:

Zettels or main notes or however one might want to call them make up the bulk of the cards. They have the famous unique Luhmann numbers.
Bibliographical notes are second largest group. Each card contains the bibliographical data of one source.
Reading notes are often overlooked as a separate type, because Luhmann wrote those notes on the reverse side of the bibliographical cards.

Secondary types:

The keyword index is necessary as entry point in a paper Zettelkasten, but in a digital implementation I'd create it automatically from tags or structured data or links on zettels, bibliographical notes and reading notes. Some users might rely on full-text search.
Luhmann did have a person index, but didn't use it much. Like the keyword index I'd create it automatically from data stored in zettels, bibliographical notes and reading notes.

The other types found in Luhmann's original zettelkasten contain simpler bibliographies and a few other kind of notes.

I wouldn't treat the "Inhaltsübersicht" as a separate type. Top-level zettels are still zettels, they just have a special place in the numbering system. However, Luhmann did in fact write a "Abteilungsübersicht" for ZK I (facsimile).

In a "basic model" you might add the concept of "patterns" for zettel content. You find recurring elements like own thoughts, literal quotes, reference lists, footnotes, mini-indexes, etc. I don't consider them proper note types, because they can appear anywhere on a zettel, can be combined on the same zettel or span multiple zettels.

Edmund · September 21

@harr said:

@Edmund said:
1. Luhmann's Zettelkasten
Let us start with my basic model of Luhmann's analog Zettelkasten system. It consists of two slip-boxes, a main slip-box and a bibliographical slip-box, each of which is focused on different types of notes. All in all, I've found five types of notes in the shown reference.

After I had a closer look at the digitized version of Luhmann's ZK, I'd group and count the types somewhat differently.

Thank you for all your suggestions. I had to re-read some sources, especially those from the Niklas Luhmann Archive at https://niklas-luhmann-archiv.de/nachlass/zettelkasten/.

And now have an updated version:

I have two open questions about your visual:
1. What are the three sections? Two physical ones and one called 'Others'?
2. What is the meaning of the red rectangle containing five types of notes?

harr · September 21

@Edmund said:
1. What are the three sections? Two physical ones and one called 'Others'?

They are logical sections, not physical ones. Luhmann's Zettelkasten has 27 drawers ("Auszüge"). 24 in big boxes, 3 in separate small boxes.

The drawers 1 to 7 of ZK I and the drawers 1 to 14 of ZK II contain zettels.
- ZK I Zettel 1 (1)
- ZK II Zettel 1 (1)
Drawers 15 to 20 of ZK II contain the bibliographical apparatus. As far as I know, it starts with letter "S":
- ZK II (Abt. Bibliographie 2): Zettel 00001
Drawer 17 of ZK II also contains a small section with indexes and other notes:

Here's the official list of the drawers and their contents: https://niklas-luhmann-archiv.de/bestand/zettelkasten/auszuege

What is the meaning of the red rectangle containing five types of notes?

It's just a highlight. Look at these and ignore the others. :-)

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