If we’re reading a web page and notice that it relates to some PDF on our hard drive, we have no real way to make that association. But we can create a note which links to both resources.
This is different from the memex solution (Bush, 1945), which imagined direct linkages between documents of any kind—yours or others’.
Writing a note is good because it forces you to Do your own thinking, but it’s a bit heavy because Evergreen notes should be concept-oriented. So to write the note, we have to extract the conceptual link between the two, name it, and arrange it in some way that might attract future linkages.
When we Write about what you read to internalize texts deeply, we have two layers of notes: there are lightweight notes about the reading itself in our reference library, then there are higher-fidelity Evergreen notes in our note archive. It may be valuable to support two layers of noting about association fidelity as well: one could make lightweight associations between materials, then encode the valuable observations into durable notes over time.
Bush, Vannevar. “As We May Think.” Atlantic Monthly, July 1945.