Three kinds of slipbox notes
Ahrens says we may divide notes into three kinds:
- Fleeting notes
- Book notes
- Permanent notes
Fleeting notes can be taken on any medium, even a napkin, and should be processed within a day or two. When in doubt, everything's a fleeting note: even underlined sentences in books or copy-pasted book excerpts count as fleeting notes. Only if you write something in your own words can it be permanent.
Book notes
Book notes, or if we put our hipster glasses on, bibliography notes or bib notes, are supposed to remind you about the content of a book (or article or anything you read). Like the main slipbox, they are permanent, but they live in a separate collection.
Why? Because in the end, any insights you got from the book should go into your main slipbox, which cannot sensibly be organized per anyone else's structure, let alone organized by which book said what. The idea is to dissolve the books: they are scaffolding wrapping up a bunch of ideas and you want to free the ideas from their prison to plug more easily into your other ideas.
Bib notes are not true members of a slipbox, even if you could treat them that way in a digital slipbox. If you were using a classic pen-and-paper system, Ahrens suggests that you use Zotero for your book notes. That's total separation!
You would not want to spend too long making bib notes, so they're short. They chiefly mention chapters that caught your attention at the time of reading and why, and you can express all that with short keywords if you like. They are not to be complete summaries of what the book was about, just the parts that you found personally relevant at the time. For books that contained a lot of new insights for you, expect the notes to be longer.