Summer is the time for post cards from friends in exotic places that help us escape our mundane lives at home. And tomorrow night "Postcard From Morocco" arrives in Washington, sent by the Wolf Trap Opera Company from the pen of Dominick Argento.

In "Postcard," Argento has created that rare work of art: a contemporary opera, daring in construction, critically successful and immune to the ill effects of time since its premiere in 1971 by the Center Opera Company in Minneapolis.

When the Pulitzer Prize-winning composer moved to Minneapolis in 1957 he could not have envisioned the path he would follow to achieve his success. "It seemed like artistic suicide to come all the way out to Minneapolis," he says.

He took a teaching position at the University of Minnesota "out of desperation" after finishing his doctoral work at the Eastman School of Music in Rochester, N.Y. Minneapolis "wasn't exactly a cultural desert" in 1957, but it was not an ocean of opportunity either.

But Argento was fortunate to have arrived the same year as two other artists, Stanislaw Skrowaczewski, the path-breaking music director of the Minnesota Orchestra, and Tyrone Guthrie, the aging British theater master.

*He worked with Guthrie at the Guthrie Theatre, writing incidental music for Guthrie's plays. The experience was vital in Argento's growth as an opera composer. "The most critical thing for me was just being around him while he was staging the plays," Argento says.

In 1964 Argento founded the Center Opera with the assistance of the Walker Arts Center in Minneapolis. He composed "The Masque of Angels" for the premiere season of the company, which has become his most important resource and affiliation.

"Like the plague, every seven or eight years I provide another work," he says. Thus in 1971 the Center Opera, with a stronger company, premiered "Postcard."

*By the early '70s, the Center Opera's relationship with the Walker was like that of the tail wagging the dog. So Center Opera split off to become the independent Minnesota Opera Company. Now it is recognized as one of the most innovative in the country. Ninety percent of its productions are contemporary and it has had 36 world premieres in just 20 years.

Before going to Eastman, Argento received his bachelor's and master's degrees at the Peabody Conservatory in Baltimore. He had gone there in 1947 as a budding pianist, but soon switched his major to composition. "With 600 students attending Peabody, I found that 599 played better than I," he says.

In 1951, he received a Fulbright scholarship to study in Florence with Luigi Dallapicolla in 1951. Though he says he didn't see much of his teacher because Dallapicolla was flitting about Europe on conducting assignments, he did learn one important thing from the master, that "one can write 12-tone music while still being lyrical."

He also fell deeply in love with the city of Florence, returning for two Guggenheim fellowships, and, beginning in 1964, spending most of his summers there. For nearly 20 years Argento and his wife, soprano Carolyn Bailey, have returned to the penthouse apartment overlooking the Arno river near the picturesque Ponte Vecchio.

In Florence Argento finds the solitude necessary to get much of his composing done. Perhaps more important, he finds "a lot of spiritual strength" in the city of such artistic masters as da Vinci, Botticelli and Michelangelo.

Argento has taken the position that in setting words to music it is "more compelling" to look to private works, such as letters, than public works, such as poetry or prose. Winning a Pulitzer Prize for his biographical song cycle "From Virginia Woolf's Diary" in 1975 confirmed that view.

Several American conductors have shown interest in Argento's work, with recent orchestral commissions coming from Leonard Slatkin in St. Louis, David Zinman in Baltimore and Neville Marriner in Minneapolis. "The more American conductors we're getting in major orchestras, the more performances of American composers we're getting."

When Argento received the libretto from author John Donahue there were very few specific instructions. Donahue even let Argento choose which characters were to sing the various lines of dialogue. Argento recalls dividing the material almost evenly among the cast, making "Postcard" "the most democratic of operas."

A good description of "Postcard" comes from Donahue: "The scene is like a memory from 1914 , like an old post card from a foreign land showing the railway station of Morocco or some place, hot and strange, like the interior of a glass-covered pavilion or spa."