"Oklahoma!" is history-making as the first show in musical theater to use dance to advance the plot so successfully and extensively.

Agnes de Mille, who choreographed the first production of Richard Rodgers and Oscar Hammerstein II's "Oklahoma!" in 1943, was among the great ensemble of choreographers of the 1940's era, including George Balanchine in classical ballet, Gene Kelly with dance in film, and Martha Graham, a pioneer of modern dance.

It was an exciting time for dance and "Oklahoma!," through June 30 at the Pennsylvania Shakespeare Festival (PSF), is a landmark of the era. The choreographers recreated the American dream through their vision of dance.

Stephen Casey is the choreographer for PSF's "Oklahoma!" Casey danced de Mille's staging of "Oklahoma!" as a young dancer and was fortunate enough to have the history and the motivation of her choreography passed down to him.

"It was not my goal to re-stage de Mille's work, but to pay homage to it, and hopefully to remain stylistically correct to de Mille's original vision that she so meticulously created. The dance had to be motivated, and it had to tell a story, which is the key.

"In this particular show, dance is scripted for many of the characters.

"Dancers were integrated within the cast as distinct characters and not just part of a chorus of dancers. The psychological and emotional struggles of the characters were expressed through dance, especially in the Dream Ballet."

Dennis Razze, PSF associate artistic director who directed PSF's "Oklahoma!," adds, "Like great orchestral music, de Mille had developed dance themes throughout the show for each character or group of characters and she varied and developed these motifs throughout the play and mostly in the Dream Ballet."

Early on in the show, Will Parker (Sean McGee) returns from Kansas City, showing off the steps he learned such as the "two-step" and "ragtime," as well as his talents as a rope-thrower and cattle bronco. The "Kansas City" number portrays the excitement of Will and an ensemble of his eight cowboy counterparts as they tap and western clog away in fancy cowboy boots with taps attached.

Before the "Dream Sequence," or "Dream Ballet," as it is known in "Oklahoma!," an ensemble of eight women dance in a circle with Laurey (Christine Negherbon), trying to make up her mind about who will take her to the Box Social, her beloved Curly (Doug Carpenter), or the shady and sullen farmhand Jud (Brent Bateman).

The circle represents unity in gathering within the community. It's also symbolic of the ever-present windmill and the movement of circles going faster, indicating danger. After Laurey uses smelling salts to make up her mind, she falls asleep and the Dream Ballet unfolds.

"De Mille developed this piece in a highly-artistic way, yet commercially accessible, which is a balance that is still sought by any generation of dance artist and choreographer for contemporary musical theater," says Casey.

In the Dream Ballet, Laurey reveals her hopes, her fears and her inner conflicts.

"The biggest challenge was that in previous productions the Dream Ballet was performed by dancers and not the main characters, as well as the score was usually rearranged and re-orchestrated. But in this production, there was no such luxury because the main characters danced the ballet themselves," Casey says.

Casey had to fit all of the nuances of the music that inspired certain steps to portray particular characterizations of movement and stay true to the story unfolding as to the fate of Laurey, Curly, and Jud as expressed in this intricate ballet.

A duet by Laurey and Curly has lifts and balletic remnants. The cowboys pretend to ride their horses, a representation also used by de Mille. Another iconic section is the mock wedding of Laurey and Jud.

Suddenly, six can-can dancers appear, representing the actual dream girls of Jud, who has photos and posters of them on his Smoke House bedroom wall. The chorus girls dance with chairs and taunt Laurey to be one of them and go with Jud.

Jud lifts Laurey and sweeps her away. An impressive fight scene, choreographed by PSF fight directorRick Sordelet, occurs between Curly and Jud.

Elements of square-dance patterns, forward and back, do-si-do, slides, bell kicks, struts, barrels, virtuosic leg extensions, partnering lifts, and of course, the can-can are embellished and incorporated in PSF's "true to the time period" production of "Oklahoma!"