It can be fascinating looking at how one invention spawns worlds of innovation due to advances the first breakthrough allows.

Personal computers have done that in our lifetimes. A few generations earlier, the harnessing of electrical currents did much the same.

Characters in Sarah Ruhl's imaginative comedy "In the Next Room, or the Vibrator Play" tug light switches on and off, marveling at simply seeing electricity work.

At Capital Stage, this incredibly funny and affectingly poetic play receives a flawlessly executed and performed production.

Director Peter Mohrmann draws on the visceral intimacy of the Capital Stage space, orchestrating perfectly calibrated performances from his remarkable cast, particularly a radiant Elena Wright as Catherine Givings. Wright's Catherine is petulant, playful, moody, curious, sexy and a little bit spoiled. Most of all, though, she has a captivating honesty and awareness of feelings that make her completely appealing.

The time is after the dawn of the Electrical Age in the mid-1880s. Ruhl's play sits at the end of the Victorian era and beginning of the machine age, but she's most interested in the social and personal institutions that are breaking down and being expansively reimagined at the same time.

Of all the breakthroughs electricity created, there was none more unlikely than the machine devised by the scientifically progressive Dr. Givings, a specialist in gynecological and hysterical disorders. Unerring Michael Stevenson's buttoned-up Dr. Givings is a quintessential Victorian scientist who would rather kiss his young wife's forehead than her offered lips. Wife Catherine would happily have her husband experiment with his machine on her.

Dr. Givings has created a machine that allows him to create a paroxysm in his patients, mostly female, to treat their hysteria. As Dr. Givings treats nervous patient Sabrina Daldry (Katie Rubin) with the machine, we recognize the paroxysm as a human reaction we call by a different name. Masterly, Rubin delivers a signature comic performance in a quietly difficult role that could easily go off track but never does. Instead, it subtly binds together several threads of the production.

Also coming into the Givings' household is Victoria Alvarez-Chacon as the marvelously taciturn wet nurse, Elizabeth.

Elizabeth feeds Catherine's baby because the young mother cannot generate enough milk, adding to her sense of personal inadequacy.

Shannon Mahoney as Dr. Givings' coolly efficient nurse Annie, Kirk Blackinton as excitable artist Leo Irving, and Greg Alexander as the hopeful Mr. Daldry are all superb, as well.

Stephen C. Jones' ingenious split-level set design opens us up to both rooms of the Givings house simultaneously, and Gail Russell's exquisite costumes add a significant layer of authenticity to the production.

Ruhl's play begins as a randy but thoughtful sex comedy, however, it evolves into something more fulfilling in its surprising second half.

There are rare occasions when elements of a production flow together so flawlessly that all you really want to say is "don't miss it."

This is one of those.

IN THE NEXT ROOM …

4 stars

What: The Sacramento premiere of Sarah Ruhl's thoughtful, very funny and maturely sexy play "In the Next Room, or the Vibrator Play." For mature audiences.

Where: At Capital Stage, 2215 J St., Sacramento;

When: Continues 7 p.m. Wednesdays, 8 p.m. Thursdays-Saturdays and 2 p.m. Sundays, through Feb. 26. Special 8 p.m. Feb. 14 performance.

Tickets: $20 to $32. Student rush tickets are $12.

Running time: Two hours and 20 minutes, including one intermission.

Information: (916) 995-5464, www.capstage.org.

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Call the Bee's Marcus Crowder at (916) 321-1120.

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