I believe everybody should eventually write their autobiography to show those who come afterwards how to be ambitious and what pitfalls to watch out for. But when we sit down at our word processors and think of what to write, our brains usually freeze over.

Not every form of literature comes easily to us. Most of our communication comes from daily chatter about the hustle and bustle of our adaptive lives, and writing what amounts to an epitaph requires a whole different perspective. In the normal course of events, it's only when we're helping someone in a crisis who we care about that unambiguously meaningful words start to flow out of us with an urgency all their own.

We write best when we know who our audience is — what culture they're from, maybe how old they are, how much we can assume they already know. For most of us, it's too hard to write for "all future generations of mankind" the way most great writers learn to do.

This is why some people feel that letter writing is the most revealing of literary forms. When you write to a loved one you cut out all the bullshit. When you write a textbook you leave in all the bullshit you can sling. Great books are a happy marriage of candor and thoroughness. Too many would-be great books are just massive piles of bullshit that quickly decompose and blow away.

Compared to prose, poetry can be an almost useless form of literature. Poetry can assent eloquently to what we already know, like Edna St. Vincent Millay, but I've never read a poem that showed or taught me anything new.

It's easiest to teach new ideas in non-fiction. But you can also do it in fiction by presenting a picture of a situation that a reasonably sensitive but curious reader has never experienced. In fact, the rise of fiction was considered by the Enlightenment to be an important aspect of the moral education of the masses. I wish it had always fulfilled that promise.