Opera composers often have turned to plays as inspiration for their dramas in music. Chance has brought two such operas in succession to the Kennedy Center, Carlisle Floyd's "Of Mice and Men" and the Gershwins' "Porgy and Bess."

Both began as novels, progressed to the theatrical stage and from there to the opera stage. While it's irrelevant, Floyd and Du Bose Heyward, whose novel was titled "Porgy," both were born in Charleston, S.C., the setting for "Porgy and Bess." Both revivals come to us from the Houston Grand Opera.

In both, the plays' dramatic structure has been followed in the opera. In both, the characters are simple people; there are no traces of gods, pharoahs, Swedish kings or dukes on the loose.

Floyd had what must be a common experience for composers who decide to stick closely to the dramatic source. He has remarked about "Of Mice and Men":

"The libretto was quickly written, with so little effort that I was disturbed. It was only after much of the first version was done that I realized that something was radically wrong. I had been too faithful to the John Steinbeck book and in a way that stifled me creatively. The book is so pared down, so lean, that I had mistakenly though that I could use it as a libretto as it was. I tried, without referring to either the novel or play, to translate it into really operatic terms, so it is complete rewrite from the skin out, as it were."

But the play's structure was firmly in Floyd's mind and by working within this he was able to convey in music what Steinbeck left unspoken.

The duet of Lenny and Curlkey's wife is striking in its intimacy of understanding, which heightens the violence that so quickly follows. This is as creative a slice of music drama as any since "Porgy and Bess," the Gershwins most ambitious work. The play's major events are the areas where Floyd's creative imagination is most free.

Heyward's wife, Dorothy, a former student of George P. Baker's 47 Workshop at Harvard, guided him in shaping his novel to stage. Their 1927 stage work, which became the firm structure for the George and Ira Gerhsim score, is followed most closely. Few recall that music became closely. Few recall that music was integrated into Rouben Mamoulian also would later stage "the American folk opera," as it was then described, when Todd Dunca and Anne Wiggins Brown became the first to sing the roles. Ira Gerchwin was ambivalent about that "for the many and not for the cultured few.

The general huzzahs that have greeted the House version as "the first production as its creators conceived it" give too much adulation to what was written in the manuscript.

Operatic composers were and are forever making changes from one production to another. There is "Paris version" of this and "the Munich version" of that and much tinkering by composer and librettist has been the rule, not the exception. Many operas as well as plays would be forgotten if manuscripts were left as written.

Therefore, welcome as is Houston's beautifully sung, richly orchestrated production, I find it decidedly inferior to the production that introduced Leontyne Price, William Warfield and Cab Calloway, a dazzling Sportin' Life, on 1952. It had its premiere the first of two American and European tours and lasted six years.

Alexander Smallens, who had conducted the first musical performance in 1935, led it again with unique musical insights. I was at its opening in Milan's La Scala, a first night of uncommon was the rising prima donna assoluta of the house, Maria Callas, and there were 35 curtain calls.

The difference is that the earlier version, directed by Robert Breen, made greater use of the drama with equalrespect to the music. Though the Houston version is said to be the first time the recitatives have been used, Breen used them but cut the orchestral accompaniment. This quiter parlando did not lose the worlds but also smoothly covered the three days and three nights after the storm scene, now not well defined.

By placing the "Buzzard Song" in Act I, where the Heywards and Gershwins had it in their script, loses its greater dramatic, effect just before the storm, which is where Breen positioned it with Ira Gershwin's and Dorothy Heyward's hearty concurrence.

In Act i, "Buzzards's" foreboding comes too soon, almost confusingly in performance. While Robert Randolph's movable setting for the interior of Serena's house is ingenious, something is lost of the storm's terror. Breen had his group on stage crowded, huddled, jammed into the small upper level of Wolfgang Roth's set, adding to the horror. It was an unforgettable effect. So was Breen's use of shutters slamming, at first for comical, character effects, and later, in the storm scene, for wracking clatter.

Nor has enough been done in this latest version to differentiate such characters as Clara, Serena, Maria, Annie and the Strawberry Woman, as well as the different men of Catfish Row. Sportin' Life is slow to register. Here the players sing beautifully but are quite interchangable. All too often the recitatives are drowned in the orchestra's welcome, full - but overpowering - sound.

Audiences have been growing up since "P&B" went to Moscow, not, by the way, under our own cultural exchange program but through financial guarantees by the USSR. (It would lose the company more than $4,000 a week and such largesse eventually wiped out its millionaire backer, the late Blevins Davis.)

Today's audiences seem to be seeing "Porgy and Bess" not as a documentary slur on blacks but as a work of art.

No less a black writer than Lorraine Hansberry wholly deplored "Porgy and Bess" and its travels. She said: "It's fantastic to suppose art exists in some sort of removed circumstances where we can say 'Well, really, it was only a play,' where we can pretend that attitudes are not molded or deepened or affected in some profound way what all of us take into our mental beings by cultural products."

Hansberry was not alone. Many liberals were aghast that dope-sniffing blacks would be shown to Europeans. Ebony's Era Bell Thompson remarked that "it continues to prick at the sensitive underbelly of the country's number one underdog." Sidney Poitier almost backed out of the film until some changes were made. I'm not claiming that such thoughts may be valid today, simply observing that they have not surfaced the way they did then.

The film, of course, was horrible. Coming out in 1959, it was produced by Sam Goldwyn, who had upped what he was willing to pay for the rights on the basis of its international acclaim. He not only ignored the most successful stage version ever and its entire cast, but had the subsequent effrontery to replace Mamoulian, who had directed both stage originals, with Otto Preminger. I wish someone would burn the original of this slick, insulting flick.