Perhaps the two most important Broadway scores to flow from the prolific pens of the brothers Gershwin are "Of Thee I Sing," legendary because of its phenomenal success, and "Let 'Em Eat Cake," legendary in spite of its failure. These "political operettas" represented a major step toward the culmination of a shared vision.

The complete scores are rarely heard, and even more rarely performed, but Washington audiences now have the opportunity to attend concert performances of two shows at the Kennedy Center Opera House.

As a team, George and Ira Gershwin were always attempting to raise the level of quality in the world of musical theater. Going back to his earliest Tin Pan Alley years, George Gershwin longed to compose uniquely idiomatic American music set to librettos of high literary quality and social importance. He dreamed of composing the Great American Opera, a dream that was realized in 1935 when he completed "Porgy and Bess."

In his later years, Ira Gershwin, recalling stories of most of the musicals of the '20s and '30s, often lamented the paper-thin plots that he and George had to set to music. He explained that their primary producing team, Aarons and Freedley, were neither concerned with nor interested in a show with a meaningful story line.

As a matter of fact, the plot, or book, of a musical was often the last element to be considered when a show was being assembled. First the producers would get a songwriter, then a star. Almost as an afterthought did they hire a librettist, to concoct a story the producers hoped wouldn't interfere with the show's other more important elements. Ira conceded, however, that even the silliest story lines contained situations that enabled him to create the most generic love songs.

For the genesis of "Of Thee I Sing," one must go back to 1927 -- the year of the Gershwins' first attempt to create a fully integrated musical. "Show Boat" is generally considered to be the first musical show with an integrated story line, but the Gershwins' "Strike Up the Band" predated the Kern-Hammerstein show by several months.

Producer Edgar Selwyn was not like Aarons and Freedley. He engaged George S. Kaufman to supply a libretto that was unusual, even daring for its time. Although he had written and directed a number of musical shows, Kaufman never concealed his disdain for the genre. However, with the book for "Strike Up the Band," he providentially supplied the perfect inspiration for the Gershwins to create the "something different" they'd long wanted to do, including extended musical sequences in mock Gilbert and Sullivan style.

Different it was. The story concerned the absurdity and futility of war and concluded with the United States entering into battle with Russia over a tax on caviar. The show's hard-hitting plot drew good critical notices, but audiences stayed away in droves. They were not ready to accept a musical that had no "hits" and no "special material" for its stars. ("The Man I Love," a trunk song from 1924, had been interpolated into the score, to be sung by a radio star of the era, but to no avail.)

Selwyn closed the show in Philadelphia, but vowed one day to revive it, believing that the opus was fresh, different and important. His pledge was fulfilled in 1929 when George and Ira became available and reworked "Strike Up the Band" with the help of writer Morrie Ryskind, who (at Ira's suggestion) softened Kaufman's original satire by making the war a dream sequence from which the show's hero happily awakens. With seven of the original 15 songs retained, and the addition of new material including the haunting "Soon" and "I've Got a Crush on You," the show ran 191 performances -- very respectable for Depression-bound Broadway.

Gershwin, Gershwin, Kaufman and Ryskind were reunited in 1931 when they began work on a second show with a political theme. To quote George in a letter to Rosamond Walling: "Ira and I have been working on a George Kaufman book -- a satire on 'Politics and Love' -- called 'Of Thee I Sing.' It is most amusing and we are looking forward to writing a score for it."

And to quote Ira: "When we went to California for the film 'Delicious' we already had several discussions with Kaufman and Ryskind on 'Of Thee I Sing,' which they were developing. Just before we made the trip they were able to give us a 14-page outline of the libretto. In Hollywood, between hours on the film, we found time to do some work on the operetta and I returned to New York with at least two notions in good shape. One was the anthemy campaign title song (later we changed it somewhat); the other was 'The Illegitimate Daughter.' "

The Story of "Of Thee I Sing" concerns the presidential campaign of John P. (for Peppermint) Wintergreen and the attempts of his party to create an election platform that will catch the public's fancy. They decide that Wintergreen will run on the "Love" ticket and hold a beauty contest in Atlantic City to find his first lady. Wintergreen proposes to the contest winner, Diana Devereaux, but later reneges and marries his secretary, Mary Turner, the woman he really loves.

But the rejected Diana Devereaux turns out to be "the illegitimate daughter of an illegitimate son of an illegitimate nephew of Napoleon," and relations with France become severely strained. The French ambassador threatens war unless Wintergreen agrees to marry Diana, and impeachment proceedings are begun against the newly elected president. The day is saved, however, when Mary Wintergreen announces that she is going to give birth to twins and the notion to oust Wintergreen is abandoned on the grounds that never in history has a father been impeached. Relations with France are restored when Vice President Alexander Throttlebottom marries Devereaux in accordance with a constitutional ruling that states that if a president cannot fulfil his obligations they must be fulfilled by the vice president.

The score, as in "Strike Up the Band," was created in the tradition of Gilbert and Sullivan, and contained long passages and deftly rhymed patter songs. But it also contained such hits at "Who Cares" and "Love Is Sweeping the Country." Gershwin's publisher decided to print the complete piano/vocal score in addition to the usual single song sheets.

A resounding triumph, "Of Thee I Sing" ran a record 441 performances, becoming the longest running and most successful Gershwin musical. It was also the first musical comedy to win a Pulitzer Prize, awarded to Kaufman, Rysking and Ira Gershwin for the libretto and lyrics. George Gershwin was not included because at the time no Pulitzer was awarded for music. Ira felt so bad about receiving an award that he knew belonged as much to his brother as to himself that he split his prize money with George.

The phenomenal success of "Sing" inspired a sequel, "Let 'Em Eat Cake." The same collaborative team was assembled and George wrote to a friend:

"There's a lot of good stuff in the new show and it is funny to beat hell but it seems to me it still lacks a little love interest. If the show is funny enough people won't mind that and Boston will tell us everything. After all, this is an entirely new kind of show and it is very hard predicting what the audience's reaction will be."

In 1959, Ira recounted: "If 'Strike Up the Band' was a satire on war, and 'Of Thee I Sing' one on politics, 'Let 'Em Eat Cake' was a satire on practically everything. Straddling no fence, it trampled the extreme right one moment, the extreme left the next. Kaufman and Ryskind's libretto was at times wonderfully witty -- at other times unrelentingly realistic in its criticism of the then American scene."

The climate in America had changed and the Depression had worsened. The bitter and biting satire of "Let 'Em Eat Cake" was not the kind of entertainment the public wanted. It received poor critical notices and closed after a dismal 90 performances. In spite of the book's failure, "Cake" was, musically, a show that represented major advancement in George Gershwin's compositional and harmonic style. It reflected his recent studies with musical theorist Joseph Schillinger and some sections of the score have been compared to Alban Berg.

After it closed in 1933, the original score of "Let 'Em Eat Cake" lay in obscurity for decades. In 1979 an attempted revival only reinforced the verdict of the 1933 critics: The show simply didn't work. But the music did. Carefully reconstructed from the only remaining source -- Gershwin's original manuscripts -- it sounded as original and vibrant as ever.

Revivals of "Of Thee I Sing" haven't fared much better. A 1952 revival featured updated Ira Gershwin lyrics and stage direction by Kaufman himself, but the clever 1931 plot had become sadly dated by 1952. A truncated television version was attempted in 1971 and the result was simply embarrassing. It became obvious that a fully mounted revival of the political musical was not the route to go.

In recent years a custom has evolved of performing "classic" musicals in a concert setting with a minimum of book and a maximum of music -- a wonderfully workable solution to a complex problem. For the current Kennedy Center engagement, "Of Thee I Sing" is being performed with its complete original orchestrations, recently discovered in a Manhattan warehouse. (This find is not to be confused with the monumental 1982 discovery of musical theater material in Secaucus, N.J.)

"Let 'Em Eat Cake" has been painstakingly reconstructed from Gershwin's original manuscripts and is heard in a brand-new orchestration, the original charts having long since disappeared. While small sections of the score are still missing, and no one who saw the original production can remember exactly how the show ended musically, we can still hear a most authentic recreation of a major Gershwin opus performed with love and dedication.

There is much speculation these days about reincarnation and the continuation of the spirit. One cannot know where the spirits of George and Ira Gershwin reside as these words are written. But wherever they are, one can be sure of one thing -- they're smiling.