Two surprising things about Catholic theologian Saint Thomas Aquinas, who died in 1274: (1) He was fat, and (2) he was cited in the majority opinion of Roe v. Wade. As Aquinas expounds in Mitzi's Abortion, while waiting for Mitzi to make him a sandwich at the Subway where she works: "It's this inane position the church has taken lately that gives an embryo moral standing as a 'human person' from the moment of conception. It's ludicrous, but these new puppies are eating it up like kibble... Can I have a Coke, please?"

The Aquinas of Mitzi's Abortion, by local playwright Elizabeth Heffron, is a Catholic Falstaff—big of mind, soul, and body—and the play's most surprising figure. While the contemporary characters take predictably contemporary positions on the abortion debate, Aquinas is wise, magnanimous, and not particularly pro-life. He meets Mitzi in her Beginning Catholicism class, which she eventually drops for an Esperanto club: "Now that I'm having a baby, everybody says I've got to start, you know, making targeted life choices... I thought a universal second language might be more practical."

Mitzi's Abortion has been over five years in the making, and the title has consistently caused anxiety. The play is about many things—the military, dysfunctional families, Catholicism—but it is, primarily, about Mitzi, her unborn child, and its demise. (After the first preview, an older audience member walked up to one of the actors. "I liked the play," she said. "But it needs a new title." The actor responded: "Ma'am, I've never been in a play with a better one.") Heffron first pitched the idea four years ago. "Someone wanted to commission a play (I won't say who) and when I said I wanted to do something about late-term abortion, the initial reaction was like"—she jumped back in her chair, agog—"Oh dear God! I was embarrassed. I kind of lost my confidence for about a year."

But she continued working on the play, which premiered in a staged reading in 2003 at the now- defunct FringeACT Festival. Now, after three years, several staged readings, and some nail chewing about what to name it, Mitzi's Abortion opens this week. In the interim, Heffron considered alternate titles: Mitzi's Choice sounded too much like Sophie's Choice, and A Necessary Cruelty, a term used by Tertullian in the second century to describe emergency late-term abortion, was too erudite. "'A necessary cruelty' is a beautiful phrase, but it didn't fit," Heffron said. "Mine's more quirky, down-home humor." A telemarketer at ACT told Heffron how she'd been describing the play to potential subscribers: "Imagine All in the Family, but Gloria is pregnant, Archie Bunker is the mom, and Meathead is in Iraq."

The idea for the play sprung out of a newspaper article about a navy wife carrying a fetus with fatal defects, but military insurance—per the 106th Congress—wouldn't cover the induced labor recommended by her doctor. Her child, as does Mitzi's, had anencephaly, a rare condition where the stunted fetus lacks a skull, scalp, and cerebral cortex. "There are a million ways a terrible thing can happen," Heffron said. "But with anencephaly, the baby stays small and doesn't threaten the mother's life." Doctor Block, Mitzi's obstetrician, points out that the baby's growth instigates labor: "Without a forebrain and no ability to induce, Mitzi's pregnancy could last over a year." Mitzi's mother replies: "You mean my daughter's gotta carry this thing around like a sack of rotting potatoes until she drops it?" The answer, according to the law, is yes. But not according to St. Aquinas.

His theory of "delayed ensoulment" tacitly permits contraception and some abortions. He advocates an idea—shared by Aristotle and St. Augustine—that a fetus doesn't get a soul until "quickening," when its limbs, organs, and senses are developed enough to begin moving in the womb, approximately 18 weeks into the pregnancy. Until quickening, a fetus is like a carrot, frog, or cow—a living but inhuman creature. The theory of delayed ensoulment was muscled aside in the 19th century by scientists and theologians who thought that homunculi rode into women's bodies on the heads of sperm cells and were complete—just tiny—people. This theory of reproduction fell out of fashion, but the idea that egg + sperm = person with a soul stuck around.

Hence Mitzi's dilemma. Her mother is for the abortion, her husband against, and Aquinas shrugs. In yet another reversal of expectations, the most moving argument against abortion comes from Mitzi's gay friend Tim: "What if some red-state Bob-and-Nancy find out the kid they're carrying has a 92 percent chance of being gay? Do you really think for one minute they'd keep it, given an option? They don't keep their Down syndrome kids."

brendan@thestranger.com