Richard Strauss, who was no slouch when it came to writing and conducting opera, was sent when he first saw the score of "Hansel and Gretel" by Engelbert Humperdinck. He called it "a masterpiece of the first rank."

There have been times, however in the 84 years since the opera was first heard in Weimar in 1893 when warring factors have tended to diminish the true stature and stength of the opera. Its story is an adaptation by Humerperdinck's sister. Adeleid of one of Grimm's fairy tales. This, plus the undeniable charm of seeing those two lovable kids, Hansel and Gretel running around on the stage trying to stay away from the wicked witch with the Gingerbread House, spread the word that "Hansel and Gretel" was an ideal way to introduced kiddies to opera. Perhaps it is, though I think that just as good a case can be made out for "Carmen", "Meistersinger" and Falstaff."

In addition to the hazards to the rest of the audience that are created when opera houses are full of children being introduced to opera. "Hansel" has also suffered when sung by singers who are not really up to its-flight writing or who take it on as an easy assignment that does not ask of them the same kind of artistic awarenass as, say, Mimi or Micaela. But listen to Elisabeth Schwarzkopf singing Gretel or Rise Stevens was Hansel and you will quickly hear how right Strauss was in his assessment.

Or listen when a great orchestra plays the prelude or the music for the Dream Pastomime. Humperdinck was, after all, the man who not only first helped Richard Wagner get "Parsifal" onto the stage in Bayreuth in 1881; he was also the composer of several measures of the music in that score which he wrote when Wagner ran short of music for the Transformation Scene. There were, in other words, no secrets hidden from Humperdinck when it came to writing handsomely for the full Wagnerian orchestra or in the most effective use of voices.

Wolf Trap is presenting four evenings of "Hansel and Gretel" this week, beginning at 8:30 p.m. on Wednesday, Thursday, Friday and Saturday. It is one mark of the caliber of their casting that the role of the father, Peter, will be sung on Wednesday and Friday nights by Donnie Ray Albert who, on alternate nights, will be singing Porgy at the Kennedy Center in the Houston Opera production of "Porgy and Bess."

(As a further indication of Albert's versatility this summer, he will be heard at Wolf Trap as bass solosit in Hnadle's Messiah on July 31, and again on Aug. 5 and 7 in the role of Wagner in Busoni's "Doktor Faust." Porgy, Peter, Messiah, and Busoni are likely to keep Albert's voice very flexible.)

Among the others to be heard in the Humperdinck opera will be the lovely Faith Esham, alternating with Karen Yarmat as Hansel, Fredda Rakusin as the mother, Gertrude, and in the famous role of the Witch tenor John Lankston. The use of a tenor in one of opera's great black humor roles has the composer's approval. In 1910 Humperdinck came to this country to assist in the world premiere of his finest opera, "The King's Children," at the Metropolitan Opera. For that seasons's performances of "Hansel and Gretel," the Met cast tenor Albert Reiss.

Humperdinck's score is filled with some of opera's most exquistie melodies. The Sandman's song gives the right singer a rare opportunity to stop the show. Franz Allers will conduct Wolf Trap's "Hansel" with staging and sets by Nathaniel Merrill and Robert O'Hearn, lighting by Gilbert Hemsley. That is as strong a team of opera producers as you can find in the world today.

Take your children by all means. Tell them ahead of tiem what a great time they will have, even though they have to be quiet during the music. Then set them the right example.