Joan Didion an American author best known for her novels and her literary journalism
She sees the deepest value of the notebook as a reconciliation tool for the self and all of its iterations:
I think we are well advised to keep on nodding terms with the people we used to be, whether we find them attractive company or not. Otherwise they turn up unannounced and surprise us, come hammering on the mind’s door at 4 a.m. of a bad night and demand to know who deserted them, who betrayed them, who is going to make amends. We forget all too soon the things we thought we could never forget. We forget the loves and the betrayals alike, forget what we whispered and what we screamed, forget who we were.[…]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.
Reproduced from www.brainpickings.org