But then anyone familiar with Poulenc's sacred music - particularly works like the "Gloria" and the "Stabat Mater" - will know how easily, how systematically, its sweet seductiveness can lull you into submission. It's so sweet as to be almost subversive, and it's this that saves The Carmelites from a fate worse than, well, death. When the Revolutionary Tribunal finally passes sentence on the singing nuns, the word "death" is underpinned by the softest and sexiest chord there ever was. Fear is seductive.
And fear is key to the obsessive and very wordy play (by Georges Bernanos) on which Poulenc's opera is based. Fear, the last frontier; the doorway to a state of grace. Director Phyllida Lloyd and her designer Anthony Ward make that doorway the central metaphor - the opening and closing image - of their fluent and beautifully focused staging. White walls in shifting configurations, provide imprisonment and sanctuary. But there is no sanctuary from fear. Fear is the soul. And the soul is enclosed in shadows, grotesque Fritz Lang shadows cast like demons upon those white walls. Sister Blanche does not chase her own shadow; she is chased by it. Even high-backed convent chairs suggest the guillotine in waiting.
But this is a play that has been standing for too long in a kind of musical marinade. The real strength of Lloyd's production - and I doubt you'll see it better done - is the way in which she has revitalised its dramatic imperative. She really uses the music. Those brutal, melodramatic, shorn- off chords with which Poulenc punctuates the drama - like exclamation marks between scenes - are seized upon by Lloyd as points of transition, not beginnings and endings. So the whole has a fluency, a momentum, that the piece itself doesn't always earn.
Poulenc is remarkably supportive (dare I say reverent) in respect of Bernanos's words, projecting them with clarity and determination; they levitate from his score. But as librettos go, this one's a bit of a debate on the attainment of grace through self-subjugation, and for all the passing beauties, the strange and interesting refractions of the music, it's a bit like a boring dinner guest - there's no getting away.
So, a flawed piece but a flawless presentation. Under Paul Daniel's crisp direction, the beatific, harp-festooned score breathes but does not languish. The predominance of female voices does not pall either thanks to sharply defined individuals within the ensemble: Susan Gritton's high-spirited Sister Constance; Rita Cullis's commanding Madame Lidoine; Josephine Barstow's impassioned Mother Marie; and Joan Rodgers' tormented Blanche, her effulgent tone pushed excitingly in extremis.
Which brings us to Elizabeth Vaughan, hair-raising as Madame de Croissy, the elderly Prioress who will not go quietly into this long night. Vaughan still has so much voice it's frightening. And the diction. They simply don't make them like that any more.
Her death-bed delirium is in every sense the dramatic highlight of the evening. Hers is truly the gaunt face of fear, the strident voice of defiance. And when she realises that God has become a shadow to her, your eyes scan the stage and that's all there are - shadows.
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