In Joan Didion’s 1976 essay “Why I Write,” originally published in the New York Times Book Review, she lays out a template in clear terms:

“In many ways writing is the act of saying I, of imposing oneself upon other people, of saying listen to me, see it my way, change your mind. It’s an aggressive, even a hostile act. You can disguise its qualifiers and tentative subjunctives ... but there’s no getting around the fact that setting words on paper is the tactic of a secret bully, an invasion, an imposition of the writer’s sensibility on the reader’s most private space.”

Didion is quoted in the introduction to “Why We Write: 20 Acclaimed Writers on How and Why They Do What They Do” (Plume, $16 paper), edited by Meredith Maran, who is donating part of her royalties from the book to 826 National, the advocacy and literacy organization for kids.

If none of the contributors here (among them Susan Orlean, Rick Moody, Jane Smiley, Walter Mosley and Armistead Maupin) discuss the craft of writing quite that starkly, they reveal themselves in other ways.

“The only thing that makes me crazier than writing is not writing,” observes “Water for Elephants” author Sara Gruen.

Mary Karr stakes out a balance between spirit and substance: “I write to dream; to connect with other human beings; to record; to clarify; to visit the dead. I have a kind of primitive need to leave a mark on the world. Also, I have a need for money.”

Maran is interested in what drives a writer; but also in the practicalities.

“During the 1980s,” Kathryn Harrison recalls, by way of explaining how she came to write her first novel, “I worked as a book editor at Viking Penguin. I loved the job. ... But, after I’d been working at Viking for six months or so, my husband said, ‘This is really stupid. You’re working on other people’s writing instead of your own.’ ”

There’s nothing groundbreaking about such a revelation; we already know the lesson it offers, which is that if you want to be a writer, then you have to write.