As a lover — and keeper — of diaries and notebooks, I find myself returning again and again to the question of what compels us — what propels us — to record our impressions of the present moment in all their fragile subjectivity. From Joan Didion’s 1968 anthology Slouching Towards Bethlehem (public library) — the same volume that gave us her timeless meditation on self-respect — comes a wonderful essay titled “On Keeping a Notebook,” in which Didion considers precisely that. Though the essay was originally written nearly half a century ago, the insights at its heart apply to much of our modern record-keeping, from blogging to Twitter to Instagram.

After citing a seemingly arbitrary vignette she had found scribbled in an old notebook, Didion asks:

Why did I write it down? In order to remember, of course, but exactly what was it I wanted to remember? How much of it actually happened? Did any of it? Why do I keep a notebook at all? It is easy to deceive oneself on all those scores. The impulse to write things down is a peculiarly compulsive one, inexplicable to those who do not share it, useful only accidentally, only secondarily, in the way that any compulsion tries to justify itself. I suppose that it begins or does not begin in the cradle. Although I have felt compelled to write things down since I was five years old, I doubt that my daughter ever will, for she is a singularly blessed and accepting child, delighted with life exactly as life presents itself to her, unafraid to go to sleep and unafraid to wake up. Keepers of private notebooks are a different breed altogether, lonely and resistant rearrangers of things, anxious malcontents, children afflicted apparently at birth with some presentiment of loss. […] The point of my keeping a notebook has never been, nor is it now, to have an accurate factual record 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.

To that end, she confesses a lifelong failure at keeping a diary:

I always had trouble distinguishing between what happened and what merely might have happened, but I remain unconvinced that the distinction, for my purposes, matters.

What, then, does matter?

How it felt to me: that is getting closer to the truth about a notebook. I sometimes delude myself about why I keep a notebook, imagine that some thrifty virtue derives from preserving everything observed. See enough and write it down, I tell myself, and then some morning when the world seems drained of wonder, some day when I am only going through the motions of doing what I am supposed to do, which is write — on that bankrupt morning I will simply open my notebook and there it will all be, a forgotten account with accumulated interest, paid passage back to the world out there: dialogue overheard in hotels and elevators and at the hat-check counter in Pavillon (one middle-aged man shows his hat check to another and says, ‘That’s my old football number’); impressions of Bettina Aptheker and Benjamin Sonnenberg and Teddy (‘Mr. Acapulco’) Stauffer; careful aperçus about tennis bums and failed fashion models and Greek shipping heiresses, one of whom taught me a significant lesson (a lesson I could have learned from F. Scott Fitzgerald, but perhaps we all must meet the very rich for ourselves) by asking, when I arrived to interview her in her orchid-filled sitting room on the second day of a paralyzing New York blizzard, whether it was snowing outside. I imagine, in other words, that the notebook is about other people. But of course it is not. I have no real business with what one stranger said to another at the hat-check counter in Pavillon; in fact I suspect that the line ‘That’s my old football number’ touched not my own imagination at all, but merely some memory of something once read, probably ‘The Eighty-Yard Run.’ Nor is my concern with a woman in a dirty crepe-de-Chine wrapper in a Wilmington bar. My stake is always, of course, in the unmentioned girl in the plaid silk dress. Remember what it was to be me: that is always the point. It is a difficult point to admit. We are brought up in the ethic that others, any others, all others, are by definition more interesting than ourselves; taught to be diffident, just this side of self-effacing. (‘You’re the least important person in the room and don’t forget it,’ Jessica Mitford’s governess would hiss in her ear on the advent of any social occasion; I copied that into my notebook because it is only recently that I have been able to enter a room without hearing some such phrase in my inner ear.) Only the very young and the very old may recount their dreams at breakfast, dwell upon self, interrupt with memories of beach picnics and favorite Liberty lawn dresses and the rainbow trout in a creek near Colorado Springs. The rest of us are expected, rightly, to affect absorption in other people’s favorite dresses, other people’s trout.

Once again, Didion returns to the egoic driver of the motive to write:

And so we do. But our notebooks give us away, for however dutifully we record what we see around us, the common denominator of all we see is always, transparently, shamelessly, the implacable “I.” We are not talking here about the kind of notebook that is patently for public consumption, a structural conceit for binding together a series of graceful pensées; 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.

Ultimately, Didion 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.

The rest of Slouching Towards Bethlehem is brimming with the same kind of uncompromising insight, sharp and soft at the same time, on everything from morality to marriage to self-respect. Complement this particular portion with celebrated writers on the creative benefits of keeping a diary.