There’s a wonderful essay in Joan Didion’s 1968 collection, “Slouching Towards Bethlehem,” about keeping a notebook. Here’s what she says:
“So the point of keeping a notebook has never been, nor is it now, to have an accurate factual recrod of what I have been doing or thinking. That would be a different impulse entirely, an instinct for reality which I sometimes envy but do not possess.
“How it felt to me: That is getting closer to the truth of a notebook. ...We are talking about something private, about bits of the mind’s string too short to use, an indiscriminate and erratic assemblage with meaning only for its maker.
“It is a good idea, then, to keep in touch, and I suppose that keeping in touch is what notebooks are all about. And we are all on our own when it comes to keeping those lines open to ourselves: your notebook will never help me, nor mine you.”