A major reason that I've always enjoyed keeping a notebook is that it embodies my thoughts. If I replace a word in a text file nobody knows, but in my notebook there's a little strikethrough and I can remember the thought process that lead me to it.
"So the social order is protected not by preventing “self-expression” and identity formation but encouraging it as a way of forcing people to limit and discipline themselves — to take responsibility for building and cleaning their own cage" - Rob Horning
Wow. This hit hard.