The death on the guillotine of a community of 16 Carmelite nuns in the terrible days of the French Revolution is sufficiently powerful dramatic tragedy for the ending of any opera. But to many, a play that is chiefly concerned with spiritual problems-the value of daily prayer, the nature of fear, the meaning of death in the midst of life-seems a highly unlikely subject for an opera libretto.

Yet something in Georges Bernanos' play "The Dialogues of the Carmelites" magnetized Francis Poulenc from the moment he first read it. He knew that the play was "his" to put into operatic form, and in the years he worked on it, he felt that he came to know each of those 16 different women intimately.

The result, as seen in the Metropolitan Opera's superb production at Wolf Trap on Thursday night, is a unique work in which music of strong sensuous appeal provides a perfect accompaniment to the working out of God's plan.

Over an orchestra of rich textures used with extreme restraint, Poulenc offers solos and dialogues of singular beauty. His melodies, seamlessly woven into the total dramatic fabric, are among the most beautiful in all opera.

Richard Woitach conducted the Poulenc with great sympathy for the radiant musical thought, letting the singers phrases breathe as they should. The large cast is on the whole excellent. Regine Crespin, the Second Prioress of the original French production, now sings the First Prioress, giving her scenes a sense of inevitable rightness.

Maria Ewing projects immense appeal and moving sympathy as Blanche de la Force, the young aristocrat driven so much of the time by a terrifying fear of the world. Her voice is lovely and well handled except at the very top, but it is still a mezzo texture where Poulenc expected a clear lyric.

Mignon Dunn is a magnificent Mere Marie; perfectly embodying Poulenc's directions that she must often be "incredibly hard," yet always within human bounds. Betsy orden sings young Sister Constance with a sunny, geaming tone and manner that is pure delight.

John Dexter's direction is excellent right up to the final scene, where he deliberately misreads Bernanos and Poulenc. It has been improved since the Met premiere two years ago, but it still needs perfection in timing and staging.

The opera deserves a permanent place in any great house.