Most tenors at the New York's Metropolitan Opera House sing an aria and get on with the music. But on Monday, April 21, the audience attending the Met's performance of Donizetti's La Fille du Regiment were treated to something that hadn't happened in 14 years. The tenor Juan Diego Florez encored an aria in response to the crowd's enthusiasm, bringing the production to a halt while he whipped through another 9 high C's in "Ah, Mes Amis."
Purists of the modern age would be disgruntled by the action-stopping showmanship. In fact, the reason encores are so rare is that the Met regarded requests for an encore in the same vein as flash photography.
But the disdain for encores is a more modern phenomenon. Back during the 17th-18th centuries, opera divas were quite willing to encore a favorite aria. Some singers became so associated with a particular number that composers would write that signature piece into the score.
But all that changed with the reform of opera. By the late 18th-century, composers like Gluck were fed up with opera theatrics. Singers must be subordinate to the music, not the other way round. Gradually, doing whatever you wanted to do on stage fell out of fashion.
But post-modernism has been chipping away at the crusty exterior and Peter Gelb, who became the general manager of the Met in 2006, has been loosening some of the rules. Maybe someday we'll forget the plot all together (always rather thin in an opera anyway) and simply create the opera sing-along, in which the audience joins voice with the singers in chorus after chorus of favorite hits.
For more information, please see the NPR article.