It's a scenario that plays out every year, and one in which you yourself may have been an observer, or even a participant.
The audience is assembled in the concert hall, or church, or school auditorium. The orchestra tunes, the conductor appears, the conversations come to a halt, there is a welcoming round of applause. The orchestra strikes up a brief, vigorous overture. Then the tenor soloist rises to his feet and intones the opening words, "Comfort ye, comfort ye my people" - and another performance of Handel's Messiah is underway.