Luhmann's Zettelkasten

"Zettelkasten" is the German word for "slip box." Whenver Luhmann read something, he would record the bibliographic information on the source and some brief descriptive notes about the content on either side of a note card. He would store these in one box. Then, he would think about what he had read and its relevance to his work. He would record these thoughts on other cards, and store them in a second slip box.These represented atomic units of thought: one idea per card. Each note would include a unique identifier.

When writing his notes, Luhmann would think about what was already in his slip box. He would draw links between his new notes and his old ones, connecting them using the identifier. In so doing, he was able to develop chains of ideas and arguments.

Schmidt suggests that the essential characteristics of Luhmann's zettelkasten was that it involved a specific system of organization and card integration based on specific rules of numbering, an internal system of linking, and a comprehensive keyword index.

Schmidt adds that Luhmann used three specific kinds of links: 1) references in the context of a larger structural outline (similar to a table of contents or outline); 2) a subject-area index of references; 3) individual references from one note zettel to another. Understanding effective linking is important, because without links, it's easy for a note to get lost.

Luhmann described his zettelkasten as a conversant and thought partner; he valued its ability to provoke surprise and surface novel connections. It produced knowledge by putting into contact ideas that one might not have otherwise logically put together; as well, he understood that an idea he recorded at one point in time may not become valuable until it was connected to another, future idea (Schmidt).



Ahrens, Sönke. How to Take Smart Notes: One Simple Technique to Boost Writing, Learning and Thinking – for Students, Academics and Nonfiction Book Writers. Sönke Ahrens, 2017.

Luhmann, Niklas. “Communicating with Slip Boxes.” Translated by Manfred Kuehn. Two Essays by Niklas Luhmann. Accessed October 19, 2020.

Luhmann, Niklas. “Learning How to Read.” Translated by Manfred Kuehn. Two Essays by Niklas Luhmann. Accessed October 27, 2020.

Schmidt, Johannes F. K. “Niklas Luhmann’s Card Index: The Fabrication of Serendipity.” Sociologica 12, no. 1 (2018): 53—60.