What is a Zettelkasten?
In German, Zettelkasten means “slip box.” It is both a method of personal knowledge management and a physical (or digital) system you maintain. The method was popularized by German scholar Niklas Luhmann who used it as a “conversation partner” to help write hundreds of articles and books. To create a Zettelkasten, you need two compartments: literature notes and Zettels. Literature notes are just bibliographic information. Niklas Luhmann wrote the citations of resources on index cards. I keep my references in Zotero. Zettels are what you will see in my digital garden as 🌳 evergreen notes. They are not notes I would take while reading something. Rather, they are insights and my own thoughts on what I read or in general. Zettels should be one idea, called an atomic idea. Remember: Niklas Luhmann wrote his Zettels on index cards. Although they are a tidied up atomic idea, they are not immutable.
As you write Zettels, you create links between them. The more Zettels you have, and the more links exist between them, the easier it is to see where clusters of ideas form. This is the “conversation partner” aspect of the Zettelkasten. When clusters form, it shows you what you’re interested in and where you have a lot of information already created. From there, you can combine the Zettels and use them to express something larger and more complex.
You can learn more about Zettelkasten at zettelkasten.de. I also like how Bob Doto explains the Zettelkasten.