In B*Spoke's hilarious staging of Hysteria, the father of modern psychoanalysis is on the couch, writes Peter Crawley.

Last Saturday, Sigmund Freud - the father of psychoanalysis and the cartographer of dreams - turned 150. The years, however, have not robbed him of notoriety in either medical science or popular culture. "Even at this late date," read his Times obituary, in 1939, "the time has not yet arrived when a just estimate of psychoanalysis and its founder is possible.

The atmosphere is too highly charged with controversy." At this much later date, the atmosphere hardly seems defused. After generations of vilification, canonisation, repudiation and modification, Freud has lost none of his power to discomfort, or to console, in his contributions toward solving the riddle of the human mind. At the very least, the films of Woody Allen would be inconceivable without him.

"The controversy is apt to become a barren one," concluded his obituarist.

To B*Spoke Theatre Company, however, currently staging Terry Johnson's brilliant play Hysteria, that seems unlikely. In a bright rehearsal room on the grounds of Muckross Park College, Dr Freud sits before us in a tub chair. An irritated but spirited old man, he is coerced into watching the case history of one of his patients, Rebecca S, played out in front of him by a mysterious visitor named Jessica and - as historical coincidence would have it - the surrealist painter Salvador Dalí.

The scene is, literally, a pivotal moment in Johnson's play, spinning the historical characters from a surreal farce into the depths of psychological realism. In preparation for the run-through, in which her character unlocks a repressed memory linked to her neurosis, and then discovers that this memory is entwined with another - the sexual abuse she suffered before the age of five - actress Alison McKenna takes notes from her director, Loveday Ingram.

"Try to be very truthful to Freud," Ingram says to McKenna at one point. At another, she interprets Jessica's correction - "Miriam! Her name was Miriam!" - as a pointed rebuke: "Get it right, you bastard!"

No one here seems certain as to whether Freud was a saviour or a scourge.

IN A WAY, he brought this on himself. In 1885, as a young doctor, Freud observed the French neurologist Jean Charcot use hypnosis to treat patients with neurotic disorders. Developing these techniques with his friend and colleague Josef Breuer, Freud used the method of "catharsis" to treat hysteria. Hysteria, the doctors surmised, was the physical symptom of emotional trauma, the psychic scar of a repressed memory. Re-ignite the emotions, Freud discovered, and you could unlock the memory. Liberate the memory and the symptom disappeared.

In their first paper, Studies on Hysteria, Freud and Breuer famously asserted, "Hysterics suffer mainly from reminiscence." But Freud went further. Over years of treating the hysterical symptoms of his patients, he came to the conclusion that these reminiscences were shameful, painful and invariably sexual. "[ A]t the bottom of every case of hysteria," he wrote in 1896, "there are one or more occurrences of premature sexual experience". In the case of hysteria, he thought, child sexual abuse had to be the root cause - something his patients were eager to confirm.

This - even for the nerve-touching discoveries of the young science of psychoanalysis - was an incendiary thesis, and ultimately it seems to have disturbed no one more so than Freud himself. Eventually he abandoned the "seduction theory" for three reasons. First, he could not believe that child sexual abuse could be so prevalent in society. Second, his theory would have implicated his own father - Freud's siblings had hysterical symptoms. And lastly, his own self-analysis, yielding a trove of Oedipal desires, had made him aware of the power of sexual fantasy. Hysteria, he concluded, was a neurotic reflection of his patients' imaginative world, not the consequences of actual abuse. Or, to put it another way, it was all in the mind.

Needless to say this has caused ructions in psychoanalysis ever since. To his approvers his backtracking was a sign of Freud's scientific integrity. It hardly eased the moral indignation of his detractors. But the tack that Johnson takes - like JM Masson, editor and translator of Freud's letters - is that Freud suppressed his findings because they were so unpalatable to psychiatry, to society and ultimately to Freud. Johnson's play suggests that Freud not only abandoned his theory, but also his patients. "You told my mother that her memory of abuse was a fantasy born of desire," says Jessica.

Freud, already charged with establishing a career on "60 years of clinical smut," now stands accused of betrayal.

"The key point is, why did he change his mind?" says Loveday Ingram, sitting outside Freud's office, once rehearsals have finished. "Why did he change his theory? For me, what's fascinating in the play is that that change in mind is what Terry is drawing on for Freud's final hours of life: the guilt that he carries."

But you can't look at Freud without Freud looking back. And a play that routinely knocks on the locked door of the unconscious can be hard to shake off.

"I think it's impossible not to let this get in your head," she says. "Particularly the scene you've just witnessed. The process to unravel a woman's journey to discover that she's been sexually abused - it's very disturbing to unlock. The gagging and the retching every time she mentions the word 'salt' . . . I mean, I worked on this play ten years ago - I assisted on the tour of the original production - and my relationship to salt has never been the same. It's a difficult play. To unlock it to a level that hurts, I believe you have to get into it psychologically."

OF COURSE, IT becomes even more complex, because Hysteria is hysterically funny. Johnson may probe uncomfortable areas, but for much of the play there is a naked woman hiding in his closet, and all the tenets of a British sex farce - the embarrassments, the hopeless lies, the sexual innuendo and the pratfalls (or Freudian slips) are present and politically incorrect. Added to the mix is Salvador Dalí, the leading figure of surrealism, who revelled in eccentricity, self-publicity and his artistic rendering of the unconscious. The mix of surrealism and farce - the melting clocks and stray knickers - is no accident. Where surrealism sprawled bizarre fantasies upon the canvas in an attempt to lay the unconscious bare - Dalí called his works "hand-painted dream photographs" - farce lets its dirty secrets tumble out of the closet.

"You refuse to identify with the characters, or feel their feelings," Michael Frayn wrote of farce. "You reject absolutely the idea it could be you up there, so idiotically embarrassed, so transparently mendacious . . . This is what gives farce its hysterical edge."

This is also why farce, with its rampaging ids and naked desires, may be a cruder, but much more effective vehicle into the shadows of the unconscious mind.

"Have I caught what we are chasing, you and I?" Dalí asks Freud of his art. "Can you see the unconscious?"

"I'm afraid all I see is what is conscious," Freud replies. "The conscious rendition of conscious thoughts . . . You murder dreams."

A plaque outside Vienna's Schloss Bellevue hotel reads: "Here, on July 24th, 1895, the secret of the dream revealed itself to Dr Sigm. Freud." The idea was Freud's, expressed to a friend in a private letter, once he had his famous dream of Irma's injection. The dream, once unravelled, was an attempt to absolve him from the mishandling of a patient with hysteria, and so represented the fulfilment of a wish. With it he began work on his influential book The Interpretation of Dreams and helped to unlock another hidden vault of the mind.

Hysteria, although it seems as undecided about the merits and morality of Freud as a heated conference of psychoanalysts, attempts to unlock similar vaults. "It's a drama that explores the psyche and the soul, and the reasons why we're here, that flips instantly into comedy," says Ingram. "It's the humour and the horror, it's comedy and pain. And we laugh that Freud is caught out. One loves the fact that you see one of the greatest brains of the 20th century reduced to a gibbering wreck, with someone else's pants round his neck, hiding terrible secrets in his closet."

Even at his ripe old age, it seems fun that the joke is on Freud - and Freud had plenty to say about the significance of jokes. Nonetheless, at the age of 150, a man of clinical certainty and moral controversy can still send shockwaves through the mind. A blank canvas for the imagination of artists and dramatists - a psychotherapist might call this transference - the Austrian doctor with porthole glasses and a Santa Claus beard is still wide open to analysis. After all these years, Freud is finally on the couch.

Hysteria runs at Project Arts Centre from May 10 to Jun 3. The Association for Psychoanalysis and Psychotherapy in Ireland hosts Freud 150, a day of papers and discussions, this Friday, May 12. See www.appi.ie or call 01-4900055