Niklas Luhmann wrote 70 books & 400 articles in 50 years.

Their topics ranged from art to economy.

And he owed it all to his elaborate note-taking system:

He used 90,000 index cards stuffed in shoe boxes.

But you can recreate it online & 2x your writing output:


Luhman’s system is known as a Zettelkasten or slip box.

Onlline tooks to recreate it include Roam Research & Logseq.

But I prefer Obsidian.

In this guide we’ll refer to files, but keep in mind Luhmann did this all manually, which makes it even more extraordinary!


The Zettelkasten system contains 3 kinds of files:

  1. Fleeting
  2. Reference
  3. Permanent

You’ll want to set up 3 folders to house each of these seperately.


Fleeting files are akin to quick capture.

These are best for:

  • random thoughts
  • web clippings
  • meeting notes

Use 2 principles:

  1. Make it frictionless to capture info
  2. Process your fleeting files within 1 day

Reference files are where you house other people’s ideas that are relevant to you:

  • Books
  • Tweets
  • Podcasts

Use 2 principles:

  1. Make them short
  2. Write in your own words

Permanent files are where the magic happens.

As you write fleeting & reference notes, you’ll spark original ideas:

  • Write 1 original idea per file
  • Link them to related files (via hyperlink or notation)
  • Link them to the reference & fleeting notes that inspired them

Over time, you’ll build a catalogue of original idea “building blocks” that are interconnected.

Luhmann was able to use these atomic ideas in infinite variations to create long-form content.

Ex: 1 productivity idea can be linked to both art and economics in different contexts.


If you’re interested in learning more, I recommend this book: