On today’s date in 1957, the New York City Ballet staged a new collaboration between the great Russian-born composer Igor Stravinsky and the great Russian-born choreographer Georges Balanchine.

The New York City company had been asking Stravinsky for nearly a decade to write a third ballet on a classical subject to make up a trilogy of works that would include his two earlier dance works on Greek mythology, “Apollo” from 1928 and “Orpheus” from 1948.

Just as they were about to despair that Stravinsky would ever write another big ballet, he unexpectedly obliged—if not with a Greek myth, at least with a Greek WORD: He titled his new ballet for Balanchine “Agon,” the Greek word for contest or struggle.

A 17th century French dance manual provided Stravinsky with a visual image of two trumpeters accompanying a dance, and that prompted one of the Ballet’s movements, entitled “bransle simple,” which prominently features those instruments. On a more modern note, by the 1950s, as Stravinsky’s assistant Robert Craft recalled, “Something called twelve-tone music was in the air, and ‘Agon’ is about 12 dancers and 12 tones.”

“Agon” is also set in 12 scenes, and some of its movements were consciously laid out in multiples of 12 bars. Balanchine himself said in working on the ballet, “Stravinsky and I constructed every possibility of dividing 12”—which in dance terms, meant abstract solos, duets, trios and quartets to match the abstract, if eminently danceable, nature of Stravinsky’s score.