When researching the history of women's embroidery, author Rachel P. Maines was astonished to find late nineteenth century magazines carrying advertisements for vibrators alongside sewing machines and other household appliances. Even more peculiar was that  the invention was a great relief to doctors, who had been treating patients with "hysteria" by manually producing "paroxysms". The vibrator was considered a scientific tool rather than an aid to pleasure, but was nevertheless a welcome time-saving device.

That the Victorian age of invention could be plagued with such dubious theories and baffling innocence when it came to (particularly female) sexuality might beggar belief, but it makes for rich thematic drama in American playwright Sarah Ruhl's hit show. The juxtaposition of blinkered science and instinctive feeling is embodied by Dr Givings and his wife Catherine, the one geekily enthralled by Edison's experiments, the other gradually unravelling, unnoticed, as she yearns for meaningful connection.

The restless Catherine, imbued with idiosyncratic warmth by Natalie Casey, is adrift, physically isolated and unable to fulfil her expected societal roles. She cannot be a wife to a husband married to his work, nor a mother to her baby when he brusquely deems her milk inadequate. Madeline Appiah brings a dignified grace to the African-American wet nurse hired after the loss of her own child and struggling to find a balance between her duty of care and maternal grief; both women are heart-rending in their silent despair.

Meanwhile, Sabrina Daldry (a beautifully expressive Flora Montgomery) struggles to face the world at all, sensitive to cold, light and sound, but not to her clueless husband (waggish Owen Oakeshott). A dose of Dr Givings' solemnly prescribed treatment soon puts a spring in her step, but his patients' sexual awakening also leads to another kind of realisation. In Simon Kenny's clever split-level set, domestic duty and physical liberation are rigidly separated, but the challenge to such compartmentalisation becomes not just desirable but absolutely necessary for future happiness.

The setting might be historical, but the frank, funny and sometimes moving reflections on marriage, love, intimacy and the communication gulf between men and women have strong contemporary relevance – in fact, some of the candid confessions about the realities of childbirth and "marital relations" have a Victorian Sex and the City vibe. The real cure is not mechanical, but is in the power of female solidarity and the importance of the shared human experience.

In a poignant subplot, the otherwise hilariously matter-of-fact nurse Annie (Sarah Woodward) glimpses a connection with Sabrina before it's snatched away, while Catherine projects her longing onto flamboyant artist Leo (a riotous Edward Bennett), who in turn has developed a scandalous attraction for another. This descent into quasi-farce, which involves characters appearing for increasingly dubious reasons, conflicts with the later bursts of lyrical musing, and some story strands are underdeveloped. There are also a few clichéd touches and an ending that would be saccharine if not for Laurence Boswell's canny staging.

However, this is a masterpiece of perfectly pitched comedy that doesn't sacrifice humanity: droll, impish and gloriously naughty with no cruelty, smug judgement or puerile excess. Edward Bennett, in particular, relishes every charged one-liner but refrains from Frankie Howerd eyebrow-waggling; his response to the novel effects of the marvellously named "Chattanooga" contraption is a deadpan, brilliantly inflected "How odd".

This is an odd play, deliberately quirky in its delivery, but refreshingly so. Ruhl's intelligent piece is both an insightful commentary on losing sight of our true nature in our quest for modernity and order, and a gleeful, giddy romp. I'll have what she's having.

In the Next Room..., at St. James Theatre

The invention of electrical stimulation forms the basis of a joyously witty and emotionally resonant period drama from American playwright Sarah Ruhl. At the St. James Theatre.

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