Look elsewhere for a medley of the pretty songs from West Side Story. This is the jeans-and-sneakers ballet music, in which the studied nocturnal cool of the Manhattan gangs ends in a hot rumble, disaster, and apotheosis. You’ll recognize the sinister deserted street-music from the beginning of the show and the extended references to “Cool” and “Somewhere.”

The principal sections of this work can be identified as Prologue (Allegro moderato), the growing rivalry between the Jets and the Sharks; Somewhere (Adagio), a visionary dance sequence in which the two gangs unite in friendship; Scherzo (Vivace leggiero), the gangs break out of the city into open space, fresh air, and sunshine; Mambo (presto), reality returns as the gangs compete in dance; Cha-Cha (Andantino con grazia), the lovers’ first meeting based on Maria; Meeting Scene (Meno mosso), they speak; Cool Fugue (Allegretto), during which the Jets try to control their hostility; Rumble (Molto allegro), a fight ending in the death of the gang leaders; and Finale (Adagio), the love music again, the procession accepting “the tragic reality, the vision of Somewhere.” The idea is that the dance sequence distills the essence of the drama, as dance so often does so admirably.

The symphonic orchestration is in part the work of the composer’s associates, a common practice on Broadway. What results is a good deal richer in sonority than theater-pit scoring, and, at the same time, offers a smorgasbord of sounds not ordinarily heard at symphony concerts: most notably, the finger-clicking and the raft of percussion (keyboards, battery, tuned drums, and traps, not to mention the police whistle). Thought “classical” composers from Gershwin to Milhaud to the present have assiduously pursued the ideal of symphonic jazz, the end product is too often an uncomfortable mélange. (A hundred-piece ensemble reading precise notation feels inauthentic to begin with; so do the evening dress and sumptuous venue.) Here, however, the solution is seductive, for the combined allure of Broadway stage and Philharmonic Hall is precisely what defined so much of Bernstein’s career.

You will hear a virtual encyclopedia of popular jazz and dance rhythms (swing, mambo, cha-cha) and just about every kind of syncopation in the book. Eventually, the ear begins to make the connection between the Jets’ whistled salute (the first thing you hear) and the Maria motive. It is said that the composer found these and many other of his thematic ideas in the symphonic repertoire he regularly conducted.