As we approach the New Year, our thoughts inevitably turn to resolutions. Running a marathon, learning Mandarin, and reading the Deipnosophistae are among the many things I will end up not doing in 2008. Keeping a diary will appear on many to-do lists, but anyone contemplating this soul-pulping undertaking should first read Louis Menand’s New Yorker essay, “Woke Up This Morning,” on the subject. He begins with a discussion of three reasons (ego, id, and superego, for convenience) why people keep diaries, and why they often fail to record more than a week or two at a stretch:

The ego theory holds that maintaining a diary demands a level of vanity and self-importance that is simply too great for most people to sustain for long periods of time. It obliges you to believe that the stuff that happened to you is worth writing down because it happened to you. This is why so many diaries are abandoned by circa January 10th: keeping this up, you quickly realize, means something worse than being insufferable to others; it means being insufferable to yourself.

Some people possess an amazing stamina when it comes to vanity and self-importance, and the results can be horrifying. (See, for example, horizon blogger Sam Munson’s hilarious review of the diaries of Joyce Carol Oates.) When such results are validated by publication, they probably push their authors even deeper into the abyss of self-regard. Yet I suspect that for many of us, the embarrassment of rereading an old journal can have a tonic effect on our capacity for humility—which is exactly why I’ve never kept one.

Menand gives us snippets of Virginia Woolf, Samuel Pepys (of course), Andy Warhol, Ronald Reagan, Arthur Schlesinger, and Leo Lerman. The major lesson to be drawn from these vastly different documents is that a diary’s greatness lies less in portraying its author than in portraying the remarkable people its author knows. Here is a memorable description of T. S. Eliot by way of Woolf, dated February 16, 1921:

Pale, marmoreal Eliot was there last week, like a chapped office boy on a high stool, with a cold in his head, until he warms a little, which he did. We walked back along the Strand. “The critics say I am learned & cold” he said. “The truth is I am neither.” As he said this, I think coldness at least must be a sore point with him.

If a diary manages this sort of thing, it should be seen as an act of literary and historical magnanimity, not least because it saves its subjects the misery of keeping diaries themselves.