I think part of it is that paper is completely unopinionated: all it’s doing is holding whatever marks you make for later. That means your brain has to do the

I think part of it is that paper is completely unopinionated: all it’s doing is holding whatever marks you make for later. That means your brain has to do the work of deciding what marks to make and their meaning; the more work your brain does on any given task, the more memories there are for you to latch onto when remembering.