When you actually start using these, quite a few people ask about the difference between reference notes and permanent notes. The distinction relies heavily on tacit knowledge, so it's tricky to answer. Especially because an answer tailored to my own context sometimes doesn't fit someone else's. Still, I'm writing this to explain it as best I can.
In Sönke Ahrens' Zettelkasten, notes are broadly divided into three types: fleeting notes, literature notes, and permanent notes. But in fact, you can think of it as just two: literature notes and permanent notes.1 Fleeting notes simply serve to capture a thought before it evaporates. 2
Before I answer, here are a few principles worth knowing.
- A natural classification is better than a rigid one.
- When writing a note, ask yourself: "When will I look for this note?"
Telling Reference Notes and Permanent Notes Apart
First, the Zettelkasten began in academia. When writing a paper, you often have to cite references. Also, in academia, the main job itself is reading papers and thinking about them. So it's natural to write down the thoughts you have after reading a paper, just as we wrote book reports after reading books. Reference notes become necessary against this background.
Is the difference the level of polish?
No. What matters more than polish is probably where the note started from. If it's a thought that came to you while reading some material, you don't need to worry about what a permanent note is. Just write it in a reference note first. That said, if the source of the material isn't important, you can simply write it in a permanent note. For example, if you never need to cite references one by one as in a paper, or you'll never need to find that material again.
If a reference note also summarizes in my own words and adds my own thoughts, how is it different from a permanent note?
The content of a reference note written while engaging with some material may connect to your existing thoughts. Then, later, a permanent note can cite that reference note.
Also, a reference note doesn't have to be summarized in your own words with your thoughts added. As I've gone along, I've found that sometimes it's better to just copy and paste the original text. That way, when you quote that passage later, you don't have to look up the source again. Just don't copy and paste mindlessly, only to have it slip out of your memory so you can't actually use it. That's about all you need to keep in mind.
Do literature notes hold only my understanding of the book, with derived thoughts going into permanent notes and the two linked together?
Yes. As you try to do it that way as much as you can, you'll get a feel for which derived thoughts end up in a reference note and which in a permanent note. I think this depends not only on what kind of thought it is but also on your computer skills. If creating and linking new notes isn't smooth, you'll find linking permanent notes a hassle and stop doing it.
Writing Reference Notes
Should multiple thoughts about one source go into a single reference note, or be split up?
Another one of my principles is "If you're torn about whether to split, don't." When you write reference notes on paper, the margins can force a split. Whenever possible, writing them in a single note will be more convenient. In any case, a permanent note can link to a specific part of a reference note with a block link.
What do you record in a reference note?
The answer may sound odd, but you can just record "whatever strikes a chord." Write down what you think you'll use later, or what seems to resonate with you.
If you want to quote the original text as is, you can just copy and paste it.
You can also write something down if it matches or contradicts your existing thinking, or if you learned something new and feel you must remember it.
If you try to write too much, it becomes tiring, and you either don't write at all or rarely look at your reference notes. If you write too little, you may not be able to use them when it counts. So you have to find the balance between the two yourself.
Writing Permanent Notes
Can I understand a permanent note as a paragraph with one central sentence?
Writing it that way is fine. But how you define a paragraph differs from person to person. In a field I don't know well, I can't see the details, and the whole looks like one thing. It's like how foreigners may see East Asians as simply Chinese or Japanese, or how we Koreans tend to see the countries of the African continent as one, without telling them apart.
In a field you know well, you can see the details, so you'll feel "this is different" and naturally split things up. To go back to the earlier point, if you're torn about whether to split, don't split. Later, you'll get a feeling: "Ah, this one needs to be split."
Also, in my own experience, something that started out as about a paragraph sometimes grew into a huge note....
When a derived thought comes up while writing a permanent note, do I keep writing in the same note, or split it into another permanent note file?
Continuing from the answer above, as you come to know more, the details naturally become visible, and you may feel "this is different" in a way you didn't before. That's when you split it off into another permanent note.