2. What kind of addresses should you put on your Zettelkasten cards?

Updated: Oct 22

To watch this video on YouTube, click here.



Resources mentioned in video

  • You can get to the Niklas Luhmann Archive by clicking here. The card seen in the video can be found here.

  • Bob Doto's Zettelkasten talk (delivered during the first Linking Your Thinking conference) is here. You can read about his Zettelkasten course here.

  • Scott Scheper's 63-page guide to "Getting Started with an Analog Zettelkasten" is available for download here. Of particular relevance to the video about what addresses to put on your cards are the parts of the guide that show what to do when a number is already taken (pp. 55–56) and talk about what to do when a card could live in various places (pp. 57–59).

  • If you would like to get a copy of Dan Allosso's How to Make Notes and Write, check out this post by Chris Aldrich, which contains links to the book (you have the option of paying or not paying for it).


Do as I say here, not what you see in the video

In the video, I note that the first—and, in the college course I’m teaching, the only—branch stemming from the parent node of the mind-map representation of the Examined Life Zettelkasten is the name of the course.


If you’re thinking of creating a Zettelkasten of your own from scratch, I would recommend that you not have a single college course constitute one of the main branches or subject areas in your Zettelkasten. Check out this video if you’re interested in creating your own old-school Zettelkasten.


Video script

If you’re creating an old-school Zettelkasten, you need to give some thought to the unique identifiers, or unique IDs, that you put on your Zettelkasten cards. This is the first of two videos in which I talk about this issue.


In this video, I will talk about why it makes sense to put unique IDs on your Zettelkasten cards and then present five different forms such IDs might take. We’ll see what the IDs on Niklas Luhmann’s Zettelkasten cards look like and what those IDs look like on cards created by four other people, myself included.


In the video that will be released some time after this one, I will show some of the Zettelkasten cards created in the philosophy course I teach and explain why I have assigned to them the letters and numbers that are on them. If you want to see what those cards look like before I release the next video, check out the one in the top-right corner here.


Before we get started looking at the various options, I want to point out that in this video I’m going to be referring to a number of webpages and online videos. Rather than put the links to those underneath this video, I have put them on a page on my website and provided the link to that page underneath the video. On that page [which, btw, is this page you're currently on], you will find not just links to resources relevant to this video but also the transcript of this video and a number of the images used in it.


0. Why put numbers and letters on Zettelkasten cards

We begin by considering why it’s a good idea to put unique IDs on Zettelkasten cards.


As I have already indicated, these unique IDs typically consist of numbers and letters.


You can think of these IDs as addresses. Just as each building has an address that can be used to locate that building, so does each Zettelkasten card have an address that can be used, well, not so much for locating the card as for connecting it to other cards.

When each card has a unique address on it and contains a single main idea—or when each card amounts to what people nowadays call an “atomic note”—then all you need when making a reference on one card to another card is the card’s address—though in plenty of cases you might also want to indicate what the referenced card is about, as you can see I have done here.

If you instead have multiple ideas on a single card, then you would have to not only use an address to refer to it but you’d also have to say something like, “Look at the second sentence on the card.”


I think a case could also be made that putting addresses on your cards and making sure that each card in your Zettelkasten is focused on a single main idea can be of help when it comes to developing lines of thinking in a step-by-step, incremental manner. I’m referring here to what in German is called “Folgezettel,” which usually gets translated as “sequence of notes.”


Okay, now that I’ve given you some sense of why I think it’s a good idea to put numbers and letters on your Zettelkasten cards, let’s now take a look at five different ways of doing so.


1. The Niklas Luhmann way

Since the sociologist Niklas Luhmann appears to be the inventor or father of the Zettelkasten method, it makes sense to look at the numbers and letters he put on his cards.


You can do that by heading over to the Niklas Luhmann archive, which you can see on the screen here. If your German is überhaupt furchtbar—or if you don’t understand what I just said—you’ll want to have the page translated. I’m using the Chrome browser right now, so I’m going to click on the “translate” button.


I’m not going to explain Luhmann’s system in any detail here. If you want a detailed explanation of how he used numbers and letters on his cards, you are welcome to read through the many resources on this website.


All I want to point out as we look at one of Luhmann’s notes here is that Luhmann used both numbers and letters to create addresses for each of the cards in his Zettelkasten. Put differently, Luhmann put alphanumeric IDs on his cards.


As you can see here, it appears as though Luhmann is also putting commas in his alphanumeric IDs—but actually for Germans and people in plenty of other countries, a comma in a number serves the same function that a period in a number serves for people in the U.S. Put differently, both function as what are called “decimal markers.” So, “4 comma 1 comma 2a” in German would be 4.1.2a here in the U.S.


If we translate this page from the German into English, you can see that the commas in the numbers have been transformed into periods.


2. The Bob Doto way

Let’s now take a look at a second option. Here we’ll be looking at how Bob Doto does things. Bob is a writer and teacher. He teaches an online course on the Zettelkasten method, maintains a blog, and has written a number of books, among other things. If you check out the video of his that I have linked to on my website, you will see that Bob knows quite a lot about the Zettelkasten method.


If we go to the webpage where Bob describes his Zettelkasten course, we see some sample notes from his Zettelkasten. Here is one of them.

As you can see, Bob does not use periods. He can dispense with periods because he, unlike Luhmann, has every number followed by a letter and every letter followed by a number.


For this card here that has as its address 4A1a, Luhmann would have likely used the address of 4.1.1a.


3. The Scott Scheper way

The third way of assigning unique identifiers to Zettelkasten cards that I want us to look at is the Scott Scheper way.


As I noted in an earlier video, Scott has done some great work uncovering aspects of Luhmann’s system that many people have overlooked.


In his video titled “How Numbering Works in an Analog Zettelkasten,” Scott crawls around on the floor as he shows how he has numbered some of his cards.


One of the points he makes is that for Luhmann, the first number in a card address, even if it was just a single digit—that first number was always a number in the thousands.


That’s why, when you watch Scheper’s videos, you see that all his cards start with numbers in the thousands.


In addition, you see from the video that instead of using periods in his alphanumeric addresses, Scheper uses slashes.


4. The Dan Allosso way

The last option for putting addresses on Zettelkasten cards that I want to go over before showing how I do things is one used by Dan Allosso.


Dan is a history professor who has hosted a number of online book clubs, several of which have included a focus on note-making. Dan has put out lots of videos about note-taking and history, which you can find on YouTube. I think you will also find that the content of his videos is superior to the YouTube thumbnails he creates for them.


In addition, Dan recently released a book on note-taking and writing called How to Make Notes and Write. You can get his book using one of the links I have put on the webpage linked to beneath this video.


Just so you know, you have the options of paying or not paying for the book because Dan has graciously decided to make it available for free.


It’s in the chapter of his book titled “Making Source Notes” that Dan explains how he addresses his Zettelkasten cards. We’ll take a look at one passage from that chapter.


After giving the example of a card that has as its address the number you see at the top of the screen here, Dan writes,


“The numbers on the left of the divider are nested categories, like folders. The number to the right belongs to the actual card that corresponds with a single idea.” He adds: “[T]he overall number tells me something about how the idea is related to other ideas (the nested ‘folders’) as well as where it fits in a conversation with other ideas (the sequence number and letter).”


I think Dan's use of the forward slash here is pretty effective. The slash is a good way of clearly distinguishing between what he's calling folders, or what I would call folder cards, on the one hand, and actual notes, or what I call idea cards, on the other hand.


5. My way

Finally. It’s what you’ve been waiting for this whole time: the kinds of addresses I put on the cards in the old-school Zettelkasten I’ve been creating for the philosophy course I’m teaching this semester.


The way I do things is pretty much the same as the way Dan Allosso does things, with the only difference being that I use a hyphen rather than a slash right before cards that contain single ideas.


And the only reason I do that is that in the app in which I’m maintaining a replica of my analog Zettelkasten, slashes are not permitted in the titles of the files. (The app I’m using here is Obsidian.)


Of course, I could use a slash on my analog cards and the hyphen only in Obsidian, but I just prefer that the addresses on my analog cards be identical to the ones in Obsidian.


Alright, if you’ve been paying attention, you are now aware of five different options when it comes to putting addresses on your Zettelkasten cards. So far as I know, it doesn’t really matter which option you choose for your own Zettelkasten.


If you think it does matter, please let us know in the comments section beneath this video. Please also consider hitting the “like” and “subscribe” buttons below. If you do so, that’ll put a spring in my step.