In the final scene of Claudio Monteverdi's last and greatest opera, Nero is embracing Poppea, his former mistress who has just become his wife and the Empress of Rome. "O mia vita," they sing, "o mio tesoro"--"Oh my life, oh my treasure," in the handy subtitles provided for the television audience. It is love music of great intensity and sweetness, remarkable in any case but particularly remarkable as the work of a 75-year-old composer.

The eye of the camera, guided by the vision of director Jean-Pierre Ponnelle, scorns such sentimentality. It moves back to point out ironically, dispassionately, that the partners in the duet are not really singing the same kind of love song. While Nero is stroking Poppea, she is embracing her newly gained crown, clutching it to her breast, running her hands ecstatically over its curves, and her back is turned to the man who has just made her the most powerful woman on Earth.

This camera work is one way of summing up what "The Coronation of Poppea" is all about. Midway through tonight's telecast on PBS (8 o'clock, Channel 26; stereo simulcast on WETA-FM), the poet-philosopher Seneca finds another way: a single philosophical sentence: "The wrong side always wins, when force wars with reason."

His words are prophetic: The sentence comes in the middle of a violent argument with Nero over his plan to divorce the Empress Octavia and marry Poppea. "I am determined," Nero snaps, and by the end of the scene Seneca's days are numbered; Poppea will engineer his death, and the only voice of reason at the imperial court will be silenced.

Seneca dared to pit reason not merely against force, but against the god Eros, the most powerful, willful and inexorable force in human affairs. In the PBS production, which had its television premiere last year, the part is sung by a boy soprano, Klaus Brettschneider, who also had the role in last week's telecast of "The Return of Ulysses." He has a clear, light voice, very blond curls and a prankish style--but he is not playing one of those cute little cupids you see in Renaissance paintings; he is a cosmic force, involved in the rise and fall of great men and nations. His sense of his own grandeur is summed up in a climactic line lifted directly from the last line of "The Divine Comedy": "L'Amor, che muove il sol e l'altre stelle": "Love, which moves the sun and the other stars."

The whole opera, complete with its subplots and seemingly random arias, is a tribute to the power of erotic passion. In this story, it is mostly destructive power and its effect is amplified when it interacts with political power. It distorts all the personalities it touches. Ponnelle is at his best in exploring these distortions, less satisfactory when he tries to be cute--by putting members of the orchestra into the dramatic action, for example.

Besides Rachel Yakar as Poppea and Eric Tappy as Nero, there are several outstanding performances. Octavia is well sung by Trudeliese Schmidt: stately and appealing as the wronged wife and deposed empress, but a tigress with ice water in her veins as she hatches a plot to murder Poppea. Matti Salminen brings a deep voice and noble bearing to the role of Seneca, and Paul Esswood and Janet Perry sing secondary roles with distinction. A tour de force is performed by Alexander Oliver in the petticoat role of Arnalta, Poppea's nurse and confidante. Bawdy, comic, occasionally sinister and strangely appealing in the little Act II lullaby, his performance exemplifies well the kind of complexity Ponnelle has found in this masterpiece. Nikolaus Harnoncourt conducts with an expert sense of Monteverdi style.