Dr. Samuel Johnson, in his dictionary, called opera "an exotic and irrational entertainment." Peter Conrad, a professor at Oxford and frequent visitor to these shores, supplies abundant details to support that definition. And all through the winter, in the Kennedy Center Opera House and the Eisenhower Theater, the Washington Opera will be providing concrete examples.

Three sopranos in leading roles will commit suicide (repeatedly!) in the eventful Washington Opera season that opens Saturday night. Another will spend long evenings disguised as a man.

For the most part, they will be doing it for love, though there will also be a bit of politics in the background when Leonora (in Beethoven's "Fidelio") puts on trousers and Magda Sorel (in Menotti's "The Consul") puts her head in the oven.

Looking at the dark side of the Washington Opera's season, you might almost think it was designed to highlight the themes of love and death -- which are timeless but have now become trendy.

Of course, the season was planned long before Conrad's book, "A Song of Love and Death: The Meaning of Opera," hit the market. So it may be a coincidence that these are the season's big themes. Or perhaps Conrad is on to something.

Love? Death? Well, sure; there's lots of that in opera. "Tosca," "Traviata," "Don Giovanni" -- all have characters who love and characters who die. But isn't opera really about high Cs and sextets and great, galumphing choruses? The average ticket-buyer, told that he is supporting a "pagan religion" that deals in "a secret and sensual knowledge," might have second thoughts.

On the other hand, encountering this statement on Conrad's first page, he might rush to get front-row seats for the season:

"Opera treats aspects of experience no other art has the boldness to address. It is the song of our irrationality, of the instinctual savagery which our jobs and routines and our nonsinging voices belie, of the music our bodies make. It is an art devoted to love and death (and especially to the cryptic alliance between them); to the definition and interchangeability of the sexes; to madness and devilment ... and to blasphemy against a Christian religion that reproves this bodily glory and chastens the organism in which the voice is warmly housed."

And you thought you just enjoyed pretty tunes.

In any case, the season will open Saturday with an archetypal love story -- Romeo and Juliet -- and will close on March 13 with another: Cinderella.

In eight productions between those dates, the company will not only present star-crossed lovers, a fairy godmother and a glass slipper; it will show (in "Fidelio") political prisoners shut up in dungeons and yearning for a glimpse of the sun; ghosts (in "Ruddigore") that lurk in ancestral portraits and come down off the wall for haunting revels; a woman (in "The Consul") caught helplessly in the gears of a totalitarian bureaucracy; another woman (a teen-age Japanese bride in "Madame Butterfly") abandoned by her American husband.

Conrad is somewhat given to sweeping statements -- an appropriately operatic quality -- and if you take his dicta as absolute and universal, they can easily be disproved. He has trouble, for example, fitting "Ariadne auf Naxos" into his schema; that is an opera about opera, so the love and death come at second hand, at arm's length and with a grain of salt.

A lot of comedy fits uneasily into his generalizations, including a couple of items from the upcoming Washington Opera season. "L'Italiana in Algeri," for example, is more about women's liberation and relations between the West and the Third World than it is about love and death.

Pietro Mascagni, who composed "L'Amico Fritz," knew about the love and death routine, all right; his "Cavalleria Rusticana" works the motifs almost to death. But not "Fritz"; it may be about love in a generic sort of way, but it is not about Eros, the most powerful of the gods, in the same way that "Tristan" is, or "Butterfly," or "Romeo and Juliet."

"L'Amico Fritz" is a nice little opera about nice little people, and when it comes on in December as the first opera ever presented in the Eisenhower Theater, everyone hopes it will introduce music-lovers comfortably to a nice, middle-sized opera house. Fritz, the hero, is a wealthy, philanthropic, 40-year-old Jewish bachelor whose friends lure him into a marriage for his own good. The opera is charming, and in the "Cherry Duet" of Act 2 it has perhaps Mascagni's most perfectly polished piece of music. But you will have to look elsewhere for a song of our irrationality and instinctual savagery.

Still, exceptions are only exceptions, and Conrad's observations are valid much more often than not. The love and death motif is dominant in nearly all of the operatic Top 40 -- such works as "Lucia," "Il Trovatore," "La Boheme" -- even comedies with a certain level of seriousness, such as "Der Rosenkavalier," where nobody dies but the Marschallin's intimations of mortality are the deepest and most memorable element.

Spoken drama deals with love and death, too, of course, and sometimes at a considerable level of intensity. But in a well-done opera, you experience the emotional impact of these motifs with a depth, an immediacy and a sustaining power unknown to the spoken theater. The secret lies in the music, slipping its message of raw feeling past all the monitors and alarms that the superego has set up to filter purely verbal input.

To do this, the music does not have to be classical; the theatrical vehicle does not have to be a traditional opera. In the past year, thousands have walked out of "Les Mise'rables" shaken to the core and unable to explain why in terms of the show's hectic pace, improbable and overcrowded plot and one-dimensional characters. Music can work on you without being understood, even -- as in a movie sound track -- without being noticed.

In opera, the music needs words, characters and spectacle to do its work, but it remains the key element. Without its music, nobody would pay 50 cents for a ticket to "Les Miserables," in spite of all the high-tech gimmickry. Similarly, modern audiences would stay away from spoken productions of "La Dame aux Came'lias" or "Le Roi s'Amuse," runaway hits when they were new, but they still flock to the operatic versions of these plays under the names of "La Traviata" and "Rigoletto."

Operatic music keeps alive dramas that would otherwise be long forgotten, hopelessly obsolete, because the music directly embodies and conveys feelings that remain valid, powerful and universal when the dialogue has become stilted, the characters implausible and the situations as old-fashioned as the costumes. Music makes audiences patient. Shakespeare had to limit his soliloquies to a few minutes maximum, but the mad scene in "Lucia" or the letter scene in "Eugene Onegin" can go on past a quarter-hour with the audience still eager for more.

When opera was invented, the Florentine poets and composers of the Camerata thought they were reviving Greek tragedy. They were mistaken in many details -- creating something completely new rather than reviving something centuries old. But at its best, particularly when it is dealing with love and death at depths far beyond reason, opera does work in some of the ways tragedy worked.

In Aristotle's theory, Greek tragedy fulfilled a psychotherapeutic role by stimulating and then purging pity and fear, emotions that the philosopher considered unhealthy. A modern revision of that theory might hold that the tragic dramas of Athens, and the archetypal myths they embodied, served a vital social role by keeping the populace in touch with the dark side of the soul. That is what opera does for its devotees.

There are differences; the Greek theater dealt with the collective identity of a closely knit society with commonly known and generally accepted myths that could be used to deepen human self-knowledge. Like Greek tragedy, opera preserves ancient mythic material and uses it for essentially the same psychological and moral purposes.

But Western man in the late 20th century has no commonly held myths -- or if he does, they are probably political and economic theories, not fit subjects for a musical drama. The stories of Tannhau ser, Violetta, Romeo and Juliet or Cinderella may be the closest equivalent we have to the community myths of earlier generations. Unlike the Greeks, we usually confront these myths as individuals, not as a community engaged in a religious rite. Except that sometimes in the opera house, when conditions are just right, the audience becomes a community with a single mind focused on a single subject. That's one of the things music can do.

The role of music is ultimately so crucial that we may see the next generation redefining opera. So far, operas have been distinguished from popular musicals by their style and technique, the range and training they require in the singers, the places where they are performed, the use of recitatives rather than spoken dialogue, etc.

But as the Broadway musical moves toward the historic end of its creative phase, a new perspective is emerging. The key questions about any kind of musical theater, opera or show, may relate to how basic themes are approached. And the music may be judged not in terms of how much vibrato the singers use or whether the voices are amplified, but on how effectively it conveys the realities of love and death.

Without formally laying down such criteria, a gradual, spontaneous reexamination of what we used to call musical comedies is now taking place. And some of them are being admitted into the repertoire of opera companies, not only in New York and Houston but in Vienna and Paris. At the same time, "West Side Story," "South Pacific," "My Fair Lady" and "Carousel" have been rerecorded using operatic rather than Broadway voices. This is not merely a gimmick; it represents a dawning knowledge that, on the deepest level, these "shows" have more in common with "Rigoletto" than with "Auntie Mame" or "Kiss Me, Kate." Among the most recent pieces of musical theater, "The Phantom of the Opera" -- despite its operatic setting -- seems to be a musical, while "Les Mise'rables," a show full of love and death and music that works on the subconscious, is really an opera.

It will be interesting, a generation from now, to see what verdict history passes on other items of the repertoire. It is probably safe to bet that "Fiddler on the Roof," "Sweeney Todd" and perhaps even "Guys and Dolls" will find a place among the operas, while "L'Amico Fritz" and "L'Italiana in Algeri" may end up (along with "Pal Joey" and "The Boys from Syracuse") in the perfectly honorable category of shows.

At least, that is what we may expect if the love and death motifs are as vital as Conrad says they are, and if opera is defined as the genre where music functions organically rather than decoratively.