A grim irony tempers the prettiness. During intermissions on those evenings when the diadem is visible it's not unusual to overhear reminiscences about Santa Fe's productions of 'Madame Butterfly' in the 1960s. The distant twinkle was incorporated into the staging, oldtimers say, and it was at the lights of Los Alamos that Cio-Cio-San gazed when she kept her vigil over Nagasaki harbor. Typically the conversation comes to an end when someone points out that the Japanese city in which Puccini's opera is set was one of several whose residents were -- in the summer of 1945 -- on the receiving end of Los Alamos' most famous export product.

The Santa Fe Opera has not presented 'Madame Butterfly' since 1972. One can speculate about the reasons for the work's long absence from the company's active repertory, but it's certain that not among them is any wish on the part of the administration to downplay the symbolism of the rural community that gave birth to the atom bomb.

'They saw a blinding white flash in the sky, felt a rush of air, and heard a loud rumble of noise followed by the sound of rending and falling buildings,' screams one of the inmates of an insane asylum at the beginning of the second act of Hans Werner Henze's 'We Come to the River,' a 1976 opera that was given its American premiere by the company earlier this summer.

The account is intermixed with tales of lynchings, torture and genocide to form a litany of 20th-century horrors. This relatively passive scene offers the audience a respite from the violence that's depicted with detail in a work the composer says is 'the expression of the convictin that we can have a rational relationship with the world and each other.' However one reacts to Henze's Marxist politics, it remains that 'We Come to the River' is one of the strongest statements of anti-war, pro-humanity sentiments ever expressed in a theatrical medium. The theme takes on overwhelming force when cast in quasi-epic form by librettist Edward Bond and sparked to life by Henze's hard-driving score. It is only in retrospect that the opera perhaps seems overly moralistic -- while it unfolds it is compelling, and it sustains Henze's reputation as one of today's most facile operatic craftsmen.

'We Come to the River' is the fourth of Henze's works to be introduced to American audiences by the Santa Fe Opera. In 1965 the company presented the U.S. premiere of 'The Stag King'; two years later general director John Crosby produced the 1951 'Boulevaad Solitude,' and the next season featured the 1966 opera 'The Bassarids.' In 1985, the company will present the American premiere of Henze' newest opera, an allegedly 'happy' piece titled 'The English Cat,' first seen in Stuttgart a year ago.

The attraction of Henze's music to the company is understandable.

Although in the mid-1950s Henze served on the faculty of the famous Darmstadt Summer School for New Music, he never advocated the cerebral constructions or arid sonic landscapes for which his colleagues Pierre Boulez, Karlheinz Stockhausen and Bruno Maderna campaigned. 'Singing is, quite simply, the manifestation of life,' Henze says in one of the essays included in his 1982 'Music and Politics: Collected Writings.' Indeed, even the instrumental music he produced in the heyday of the post-World-War-II avant garde is characterized by life-affirming lyric qualities.

'My music is impelled towards gesture, concreteness, visualization,' he says in another essay; 'It sees itself as drama...and could not exist in tidy abstinence or in private domestic realm.' In this regard, too, the self-analysis is accurate; Henze's compositions for orchestra and chamber ensemble are invariably rich in 'expression' and suggested movement, and when the action is made real -- in the operas and ballets -- it simply confirms the fact that Henze's natural milieu is the theater.

In recent years Henze's music has grown increasingly eclectic, and many of the works he's written in the last decade and a half are free-flowing assemblages of such diverse idioms as 12-tone serialism, musique concrete, 18th-century counterpoint, Balinese gamelan patterns and Mississippi delta blues. 'We Come to the River' contains its share of exotic elements. One of the three groups into which the orchestra members are divided includes string players who double on Japanese instruments, for example; in one of the opera's most spectacular episodes a 30-piece military band parades around the stage while playing a sardonic parody of a Sousa march.

For the most part, though, the music is atonal and abstract. Like the make-believe land in which the opera is set the score functions according to its own bizarre yet somehow logical rules and regulations. So solidly meshed are the dissonant fragments, and so propulsive and grinding the rhythms, that the occasional references to more or less 'normal' musics serve not as focal points for the listener's attention by simply as lucid intervals in a sonic portrait of a world going mad.

The central figure is a General who, although victorious in battle, is sent to an insane asylum because his superiors fear his conscience is growing stronger than his sense of duty. The General is going blind, and as his eyesight fails he is able to 'see' more clearly the effects of his ruthlessness. Eventually his eyes are gouged out by thugs dispatched by the paranoid Emperor; feeling his way through the same enlightened darkness explored by Oedipus and King Lear, the General has visions of the innocent persons whose executions he ordered in the opening scenes.

His fellow inmates, all victims of some atrocity, at first regarded him as a potential leader; in his latest stage of development -- fully repentant but reduced to catatonic immobility -- he's considered a threat. They smother him in an imaginary river made of bedsheets and pillows. Finally united, the lunatics stand together on the nonexistant shoreline. 'If the water is deep we will swim,' they chant; 'If it is too fast we will build boats. We will stand on the other side. We have learned to march so well that we cannot drown.'

In the program note for the work's 1976 premiere at Covent Garden, Henze and Bond say that whereas the Catholic Mass celebrates man's relationship with God the ritual of the Opera's final scene celebrates 'man's responsibility to man, the cost of that in human blood and the reward in earthly happiness.' That may be overstating it a bit, but much of the opera has the air of liturgy about it, and its structure certainly has little in common with the linear 'real time' development of traditional opera plots. The primary source of dynamic energy is simply the fluctuation in intensity of the various characters' insanity. Yet the pace seems fast -- after the brutal cadence is pounded out one I left with the unsettling feeling that the real drive toward climax has just begun.

'We Come to the River' was not the only grim material at Santa Fe this summer. The company also featured a double bill of Alexander Zemlinsky's 1917 'A Florentine Tragedy' and Erich Korngold's 1916 'Violanta,' each of them based on a romantic triangle in which one of the lovers is violently killed.

His latest theatrical coup, introduced to the United States by the San Francisco Opera last weekend, is an adaptation of a Yukio Mishima novel known to American readers as ''The Sailor Who Fell From Grace With the Sea.'' Premiered in Berlin in May of last year, the new opera retains both its German libretto and its German title. It is called ''Das verrätene Meer'' - ''the betrayed ocean.'' Like its official English counterpart (made familiar by a 1976 film starring Kris Kristofferson), ''Das verrätene Meer'' is a title sanctioned by Mishima and his agents when the 1963 novel went into translation. 

"Das verrätene Meer'' and ''The Sailor Who Fell From Grace With the Sea'' are hardly linguistic equivalents, yet they represent the same basic idea - with different emphases - of bitter conflict between a sailor and the sea. The original Japanese title is less prosaic, and it focuses attention not on the book's protagonists but on its underlying philosophy. Mishima called his novel ''Gogo-no Eiko,'' which means ''an afternoon's glory.''

In the opera as in the novel, glory is something sought after but never attained.

For the sailor, glory is an abstraction left over from his past; although in his youth he envisioned himself as a hero, in his maturity he realizes he is a normal human being, and he settles - albeit not without regret - for a normal life as the landlubbing husband of a Yokohama widow.

For the widow's 13-year-old son, glory is a reality that at least seems within reach. It is only the boy, prompted by the leader of his cynical and perversely ''objective'' gang, who decides that the sailor has betrayed his ideals. By punishing the sailor, the boy concludes, the gang can bring the sailor and the sea - once again - into a harmonious relationship. In the process, the gang feels it can achieve for itself a kind of intellectual/spiritual fulfillment. These are just kids, fraught with confusion and desperate for identity; by even the loosest legal standards, their ''trial'' of the sailor is a joke. Still, they are unified enough to reach a verdict, and apparently they are strong enough to carry out the sentence. Following the example of the novel and the film, the opera ends a moment before the consummation of a ritual execution.

The plot of Henze's ''Das verrätene Meer'' varies only slightly from that of Mishima's book. Certain descriptive details are omitted, and episodes originally presented as flashbacks are re-cast into a straight-line, present tense narrative. On the whole, though, the libretto by Hans Ulrich Treichel is remarkably faithful to its source. What is grim in Mishima remains grim in Henze; what is ambiguous in the novel is just as troubling in the opera.

With a plot as powerful as this, a simple rendering - for the run-of-the-mill composer - might suffice. But Henze has never been one to opt for the merely literal approach. Beginning with ''Boulevard Solitude,'' a 1951 re-telling of the ''Manon Lescaut'' story from the point of view of Manon's lover, his operas have always been as rich with drama as with action. Henze deals facilely with the visible stuff of opera, with the characters and whatever they do in full view of the audience. More significant, he deals in masterly fashion with opera's invisible elements, with the complex, often conflicting emotions that make up the characters' psyches, with the mysterious, inanimate presences that dominate their lives.

The title role in ''Das verrätene Meer'' is played by the orchestra, a large one that calls for an expanded string section, auxiliary wind instruments and a dozen percussionists. And it is an important role, indeed, the central role.

Readers familiar with the Mishima novel, or with the film, will recall that voyeurism looms large in the story; the boy is in the habit of spying on his mother through a peephole in her bedroom wall, and his hostility stems in large part from the breathless witnessing of his mother's sexual encounters with the sailor. But for Henze - more so than for Mishima - the sea, too, is a kind of voyeur. It is always there, close to the action, and not even the opera's most private scenes escape its watchful eye.

Yokohama, after all, is a harbor city, as much threatened by the sea as nourished by it. For the mother, who runs a boutique that specializes in clothing imported from Europe, the sea is a source of income. For the sailor, it is a vast wilderness that once seemed romantic but lately has turned cold and bleak. For the boy and his gang of budding existentialists, the sea is one of the few things on earth that warrants respect.

''Each of us is a complete being,'' the gang leader preaches. ''But the world we live in is empty - a barrel run dry, hollow like the trunk of a worm-eaten tree. It's our job to uproot it. We are the ones who allow things to exist. Like this leaf, this stone. We are the ones who permit the trees to rot, mothers to cry, fathers to yell. If we had any compassion for this life, the least spark of sympathy for this world, we'd have long ago changed the stones into dust and the leaves into air. Only the least of things is bearable, the sea . . . . And if it, too, should conspire against us, it would be as if our own hearts were forcing the blood out of our bodies, as if our mouths would devour our own tongues.''

Perhaps the sea does conspire against the boys, and against the sailor. But one never knows for sure. As portrayed by Henze, it resembles the inscrutable ocean of Benjamin Britten's ''Peter Grimes.'' It speaks with a powerful, sometimes awesome voice. Yet what it seems to be saying is that it is a thing unto itself, an entity that cares not a whit for frail, self-centered mortals. Like Britten's, Henze's sea is more passive than its turbulence suggests; however profound are the effects it has on human beings, they are ultimately human effects that stem from human attitudes and - for better or worse - human decisions.

According to British music critic Michael Kennedy, who provided an article for the San Francisco Opera's program booklet, Henze regards the Mishima novel as ''a highly colored erotic drama, a triangle of passion and love.'' But Henze also sees in the book, Kennedy says, ''a layout for a Greek tragedy told today.''

Surging through most of the interludes, and occasionally welling up to comment forcefully in mid-scene, the sea in ''Das verrätene Meer'' indeed functions as a Greek chorus. At the same time it functions like a Greek god, observing everything and dispassionately allowing it all to happen.

The musical language of ''Das verratene Meer'' seems mild compared with the brutal dissonances and tortured screams that flavored Henze's theatrical works in the late 1960s and early '70s. It remains, however, an atonal language rooted at least theoretically in the serial techniques Henze learned at Darmstadt in the years just following World War II. With the standard vocabulary of this language - angular melodies, disjunct rhythms, crunching harmonies - it is easy for a composer to limn scenes of tension and violence. It is very difficult to paint softer moods, or to illustrate situations in which wide-ranging emotions are expressed simultaneously. But lyricism has always been Henze's great gift. No matter how adventurous his idiom, he manages to tell his operatic stories in a way that seems credible. And he gives his performers material they can really sing.

In ''Das verrätene Meer,'' the most urgent lines are assigned to male voices, to the tenor, bass and baritone who play, respectively, the son, the sailor and the leader of the gang. The part of the mother is scored for soprano; it is incidental to the plot, yet it figures prominently in the music, and so sensitive is its treatment that it comes across as the modernist equivalent of bel canto.

The San Francisco production runs through Saturday and features an absolutely convincing cast headed by Ashley Putnam as the mother, Tom Fox as the sailor and Craig Estep - a newcomer to major-league opera - as the son. Markus Stenz is the conductor, and the staging is by Christopher Alden.