Today, I filled in the last blank page of the diary I've been keeping since March of last year; I also finished this 1984 exploration of chroniclers, travelers, pilgrims, creators, apologists, confessors, and prisoners -- diary keepers of all stripes.
I love these sorts of surveys, and Mallon's varied examples illuminate the subject (which is, of course, a million subjects at once, all filtered through the lens of personal experience). Since so much ground is covered, perhaps a few salient quotes will pique your interest, too.
On why we keep diaries:
No one gets a thousand years; but if you're lucky you get twenty thousand days, and the chance to put down a 'million' things. ... I live a pretty quiet life. I've spent a lot of what I hope is the less than half of it that's passed reading and teaching books, and one thing I've learned is that the private fingering of ordinary experience can fill up notebooks as interestingly as musings on great events.
On failings (tied to a narrative related to May Sarton's musings):
When human beings are playing for stakes of happiness and self-knowledge, the only believable victories are probably the temporary and partial ones.
On unexpected treasures (illustrated by a perusal of Degas's journals):
The further one ventures into Degas's notebooks the more one senses a shyness, a scrupulousness, that makes moments of revelation, when they do come, all the more compelling. He does not want the clamorous fame that is sustained by ignorance: "There is a sort of shame in being known especially by people who don't understand you."
On diaries and gender:
The little girl is being trained to appreciate dailiness, and ordinariness: her lot in life is the quotidian; her brother will do whatever transcending there is to be done. But the bright little girl soon enough recognizes that the cultivated inner life can be a much more powerful and dangerous weapon with which to repel intruders than any baseball bat. It may be in her diary that she discovers how to keep part of herself back, and to take revenge on those who have wounded what part of her has been exposed.
On innovation, technological change, and the persistence of pen and paper:
We contend more with the electronic explosion of information than its technological suppression. If books soon metamorphose entirely into tape and microchip, that transformation will be a matter of economic profit and (supposed) convenience rather than fearful extirpation. You may be intellectually ecstatic or aesthetically aggrieved at the idea of a Library of Congress in a cigarette pack, but fear is not really the appropriate reaction to this imminence. As for the place of diaries in all this: if they got written by candlelight, they can presumably get written in the green nighttime glow of the word processor.