When is a kiss just a kiss?

Sarah Ruhl took her five-year-old daughter to the theater. When her daughter asked if the actors were “real people,” Ruhl realized that “she must have asked because of the profusion of digital images she sees. She didn’t wonder if the characters were real; she wondered if the actors were.”

In Ruhl’s Stage Kiss, the actors may be acting but the kiss is real. Or, are they real, and the kiss is just a kiss?

The character named She hasn’t done a show in 10 years. Took time off to raise her daughter. She’s been cast in The Last Kiss, a florid, 1930s clunker about a woman with only a month to live. Though married, the woman wants to see her first real love.

The man cast as She’s first love in the play is, in fact, her all-consuming love, He. There’s a scene where they must kiss.

In an interview, Ruhl talked about stage kissing: “How weird, to watch actors kiss. It’s their job, and that’s a wonderful job.” But is it acting? Yes, she says, “when there’s no chemistry.” But what if it’s there already? Or if a kiss can start a chemical reaction?

Case in point. She’s profoundly sane husband, called The Husband, says She and He have kissed 288 times on stage. “That’s not love,” he says, “that’s Oxytocin.”

“No,” He corrects, “it’s Oxycontin.”

No, Husband’s right. It’s Oxytocin, a hormone linked to sexual arousal, and person-to-person bonding. Could a fake stage kiss elevate its levels?

And if so, how does this true-bluest of husbands bring them back down?

I love Sarah Ruhl’s plays. She’s always doing things beyond the things you’re looking at. On the surface, Stage Kiss looks to be a humorous examination of the title. Deeper down, Ruhl explores the notion of a parallel universe and asks which is more real, daytime life or dreams, the actual or the ghost?

New Village Arts’ director Chelsea Kaufman treats the play as a backstage farce in two styles, the 1930s and today. Although Brian Redfern’s sets heighten the differences — the stage/fantasy world for act one and He’s grimy, realistic East Village studio for act two — the production stays on the surface throughout. It’s nicely done, for the most part, but there’s more to the script than on the stage.

Daren Scott stars in a supporting role. He’s Adrian Schwalbach, the driven, daffy director. His idea of a good play, as Oscar Wilde once said, “would frighten the horses.” But his love of theater — and of Ruhl’s illusions — is a saving, often hilarious grace.

As He and She, John De Carlo and Amanda Morrow beam off and on. Along with some fine fluid moments they sometimes become mechanical, thinking the next move before making it.

Dallas McLaughlin’s just right as the Husband (who, a la homeopathy, uses the illness to cure the illness). Brian Butler has fun as Kevin, the understudy, whose open-mouthed kissing technique might appeal to a grouper, maybe. Christina Flynn and Sarah de la Isla do well in supporting roles.