Here's why I know anything about jazz, or Gaelic culture, or the criminal justice system: I wanted to write a book.

Yes, NYU's continuing education program may have come in handy, a bit, on that latter one. But why would anyone bother to educate themselves on arcane knowledge just for the sake of a book? Isn't it all just made-up anyway?

Yes and no. I didn't wake up one day with a burning desire to know everything about Charlie Parker and bebop and then ran out to read all the things. I just wanted to write about someone who had Parker in her blood, in her name, in her family, in her life — and so, a bit like a Method actor might, I went to get educated. It was a delightful journey to be on, as was the one I went on to read up on Ireland and folktales and Gaelic; I recall a free lesson and a visit to a Dublin university for more research. The criminal justice system, well, if you know half a sentence about me you'll know about the decade-plus long interest in most things "Law & Order." It was a bit like a hobby, learning these things, without direct application.

Until I sat down to write. And then, having all of that acquired knowledge and sensory input and references helped immensely.

The received wisdom is to write what you know. What it means depends on a lot of factors. At 18 or 19, you don't know a hell of a lot. Later on, you know more but then life has educated you more on the gray areas and it can be a little harder to write with fiery straight-up ignorant passion. This is how we end up with memoirs from people who haven't even reached the half-century mark, or "literary" fiction of the belly-button gazing variety. Little happens and there's much interior beachcombing going on, or a lot happens and we see it through this gauzy scrim of an author who isn't able to process it properly, or just quoting her therapist's insights.

Instead, what I've found is that "write what you know" isn't the absolute. It's meant to meld with everything else you're actively going out and learning. Then, again, when you sit down to write you have the things you are making up of whole cloth, the patchwork quilt you've stitched together from research, and the inside received bits of wisdom and experience you have from your own life. The last one is what puts fuel in your story (hello, metaphor mixing) and gets it going, it's the thing that makes you passionate to write. It seeps into that writing in useful drips and less subtle swathes and the writing feels natural because, on some level, you're doing some unconscious self-examination as you write it all down. Why does this recurring relationship structure fascinate me? Ah yes, my own family setup. Why is there always one character who refuses to do this, who falls ill, who disappears? Look inside, and it's there.

"Write what you know" came up in writer's group on Tuesday; one of the participants had written a story about an abrupt move to Arizona, and how the environment was conspiring against her narrator to make her feel at home, but it was strewn with Big Metaphors and kind of didn't go anywhere. She admitted to feeling lost and unsure about rewriting, and after some time of offering advice, we landed on the fact that the desert move had come from her real life, and so there we were, talking about how what we know gets into our fiction whether we intend it or not. Our own origin stories. Life-shifting events. Major accomplishments, but more likely, major tragedies. The odd "In Search Of …" spin our lives can take. That's the place you leap off from, and the rest is very important, if secondary, window-dressing.

So maybe that's really what it means to write what you know. Memoirs may not be easy — you're baring your (colorized for maximum efficiency and verve) life, but I'm convinced that they're much easier than fiction. Memoirs hvae you telling what you remember, a bit fictionalized here, a bit fictionalized there. But creating a new world and painting it with little bits of yourself, essentially self-analyzing while self-cannibalizing, that's hard.

Because however long you decide to research jazz, or Irish language, or crime, the real research project you have the most time invested in is yourself. That's what you really know.