TheClearHorizon asked an interesting question in a comment thread over at Zettelkasten.de about a particular advantage of Luhmann’s index card system. While responding to his post, I realized that there was a certain structural feature that I had reproduced using Git without reflecting that I had done this. I would like to make two points, first a theoretical point about the architecture of a Zettelkasten and second a practical point about using Git to achieve this.

#### Theoretical Point

There are different kinds of association between ideas, and the architecture of a note-taking system can be better or worse at capturing these connections. Luhmann’s Zettelkasten system is brilliant because it captures many types of association very efficiently. Each index card has an ID that looks something like this 143b/3c/2. The first number 143 stands for a particular topic, say Sartre. Letters indicate branching within that topic. So 143b may stand for Sartre > No Exit. A slash followed by a number stands for a continuation (which is necessary because of the physical size of the index cards). So 143b/3 would stand for the third index card of Satre > No Exit. (My apologies if this is not a strictly accurate representation of Luhmann’s actual system.)

The disadvantage of this system is that the numbers are rather cryptic. On an electronic version we have the space, so we can just write Sartre > No Exit rather than 143b. We can still capture the two kinds of association between ideas that matter most: (i) explicit reference and (ii) hierarchical nesting. Subtly, however, we have just lost an important form of association: (iii) the sequential relationship between 142 and 143. 142 might stand for Drama and we would not immediately think to associate Drama and Sartre. They are associated in the numbering system because the person creating the cards first opened a new topic for Drama and then opened a new topic for Sartre. The two ideas are associated for the researcher because of the chronological nearness of the work.

#### Practical Point

One of the great advantages of working in a plain-text format like Markdown is that you can use powerful tools like Git rather than whatever your software happens to ship with. Many change-tracking features in software like Word or Dropbox happen automatically. Each time you save or make a change, the software keeps track of what you did. This is fine if all you want is to keep from loosing your work, and you can make Git work this way too. But there is a better way: make intentional commits with brief, descriptive messages that log what you have done at logical intervals in your work. For years, I have been doing this for all my writing as a matter of course.

Now the realization: I have also been using Git to get the same kind of association that I thought might be lost by switching from numbers to descriptive titles. Each time you make a commit in Git, you have a group of files that have been changed at the same time. They are “change neighbors” so to speak. With a Git plugin in Sublime Text, it takes only a few keystrokes to pull up a log of all the times a particular file has been changed. By selecting one of these commits, I can—within seconds—see all the “change neighbors” of this particular file at any stage of its development. In other words, I can easily see all the notes (whether I would later think to relate them or not) that I was working on at the same time as this note.

This method of association is actually more powerful that the association between 142 and 143 above. Those numbers were close to each other only because those top-level topics were created at the same time. Association through Git commits, however, established nearness each time the note is changed not just at creation.