(3/23/2025) In my own writing and studying, I make extensive use of a physical *Zettelkasten* (German for "slipbox"), an index card-based note-taking and personal knowledge management system that, in its current form, was popularized by the German sociologist Niklas Luhmann. Card filing systems have been around since the mid-17th century, evolving out of the commonplace book tradition—a sort of intellectual scrapbook for compiling notes, quotations, aphorisms, and anything else of the sort. However, Luhmann’s major contribution was the invention of a complex internal referencing system that allowed cards to be "linked" to other cards within the filing system. Luhmann actually called his *Zettelkasten* a "thinking partner" and credited it with enabling him to publish over 70 books and nearly 400 research papers during his lifetime. This ingenious system of internal linking preceded the development of hypertext and directly influenced the creation of much of the modern software you probably use daily without even realizing it—including Obsidian, which I’m currently using to write this blog post. I take an interest in how people organize their thinking because, in some ways, I don’t believe the mind is limited exclusively to the brain. There’s actually a [wonderful paper](https://www.alice.id.tue.nl/references/clark-chalmers-1998.pdf) I read on this subject not too long ago. I also find that studying how others structure their vast interdisciplinary interests helps me make sense of my own. Below are some interesting images I’ve come across from three separate Flickr accounts, showcasing the now-defunct PoIC (Pile of Index Cards) community. They appear to have been a small online group—mostly college students active on 2channel and Flickr—based in Japan in the early 2000s, who developed a unique take on the *Zettelkasten* method. ![[icpod.jpg]] aki oda's PoIC icpod subsystem (https://www.flickr.com/people/aki_oda/) ![[workspace.jpg]] hawkexpress' workspace (https://www.flickr.com/people/hawkexpress/) ![[card.jpg]] One of kf333's cards (https://www.flickr.com/people/36761543@N02/) Peace.