Zettelkasten has come up in productivity discussions here and elsewhere in the Macoverse. I didn’t have a good handle on what a Zettelkasten is until I found this explanation:
German sociologist Niklas Luhmann (1927-1998) conceived of Zettelkasten as a simple but powerful way to take and use notes. Sort of a personal wikipedia, based on index cards rather than computers.
MK, writing at the blog Taking Note, says Luhmann’s index cards system rejects alphabetical organization, or hierarchical categories. “Luhmann’s notecard system is different from that of others because of the way he organized the information, intending it not just for the next paper or the next book, as most other researchers did, but for a life-time of working and publishing.”
Instead, he opted for organisation by numbers. Every slip would receive a number, independently of the information on it, starting with 1, and potentially continuing to infinity. Since his slips were relatively small (slightly larger than 5 x 8 cards, or Din-A 6, to be precise), he often had to continue on other slips the information or train of thought started on one slip. In this way, he would end up with Numbers like 1/1 and 1/2 and 1/3 etc. He wrote these numbers in black ink at the top of the slip, so that they could easily be seen when a slip was removed and then put back in the file.
Apart from such linear continuations of topics on different slips, Luhmann also introduced a notation for branchings of topics. Thus, when he felt that a certain term needed to be further discussed or the information about it needed to be supplemented, he would begin a new slip that added a letter, like a, b, or c to the number. So, a branching from slip 1/6 could have branches like 1/6a or 1/6b, up to 1/6z. These branching connections were marked by red numbers within the text, close to the place that needed further explanation or information. Since any of these branches might require further continuations, he also had many slips of the form 1/6a1, 1/6a2, etc. And, of course, any of these continuations can be branched again, so he could end up with such a number as:
21/3d26g53 for – who else? – Habermas.
These internal branchings can continue ad infinitum – at least potentially. This is one of the advantages of the system. But there are others: (i) Because the numbers given to the slips are fixed and never change. Any slip can refer to any other slip by simply writing the proper number on the slip; and, what is more important, the other slip could be found, as long as it was properly placed in the stack or file. (ii) This system makes internal growth of the Zettelkasten possible that is completely independent of any preconceived ordering scheme. In fact, it leads to a kind of emergent order that is independent of any preconception, and this is one of the things that makes surprise or serendipity. (iii) it makes possible a register of keywords that allow one to enter into the system at a certain point to pursue a certain strand of thought. (iv) it leads to meaningful clusters within the system. Areas on which one has worked a lot are much more spatially extended than those on which one has not worked. (v) There are no privileged places in the note-card system, every card is as important as every other card, and no hierarchy is super-imposed on the system. The significance of each card depends on its relation to other cards (or the relation of other cards to it). It is a network; it is not “arboretic.” Accordingly, it in some ways anticipates hypertext and the internet.
Luhmann claimed his Zettelkasten system resulted in surprise insights - he referred to it as his collaborator.