Netflix recently release a documentary about Bill Gates (Inside Bill's Brain: Decoding Bill Gates) where he discussed his strategy of writing in the margins of a book while he reads.
I really enjoyed this commentary and tracked down a video where he discusses his strategy:
I think that's sort of a shame here is that the notes are encoded on paper and not really searchable.
Polar's annotation sidebar allows the user to take highlights, add comments to that highlight but also encode the annotation to a flashcard to enhance long term recall via spaced repetition.
Bill's comments made me think about another memory encoding strategy regarding the pencil in that studies show that tactile feedback of using a pencil actually increases recall.
We might (at some point) add a margin mode to Polar such that you can use a tablet with a pen and literally write your notes (figures, text, etc) in a virtual margin setup where the document has a larger margin that's indexed via Polar.
In the mean time the Polar annotation sidebar will work as a GREAT substitute though.
Here's a screenshot of my annotations on a book I'm currently reading: