The NY Times on "Brundibar", an opera written by Maurice Sendak and Tony Kushner:
This production is based on Mr. Sendak's 2003 picture book of the same name, written with Mr. Kushner, which in turn was inspired by the original opera, by Hans Krasa, with a libretto by Adolf Hoffmeister, which was first performed in 1942 at a Jewish orphanage in Prague. The score, jazzy, haunting and a little advanced for its time, combines elements of Debussy, Ravel, Berg and Gershwin, and the story is simple and affirmative: two children, Aninku and Pepicek, caring for their ailing mother, are told by the doctor that she must have milk if she is to recover. They go into town and while trying to raise some money by singing together, are chased away by a nasty hurdy-gurdy grinder named Brundibar (which means "bumblebee" in Czech). After being joined by other children and some talking animals, though, Aninku and Pepicek prevail in true operatic fashion: they raise a bucketful of cash, drive Brundibar out of town and return home with the precious, life-sustaining milk.
What gives the opera additional poignancy is that shortly before the first performance, Krasa, a Jew, was arrested and sent in an early transport to Theresienstadt, the "model camp" that was in fact a way station for Auschwitz. Under Krasa's direction, "Brundibar" was subsequently performed 55 times at Theresienstadt, with a cast of imprisoned children, for an audience that sometimes consisted of visitors sent by the Nazis, trying to demonstrate how humane they were.
"Think of it," Mr. Sendak said. "There was this bunch of children, and after every performance a part of the cast was sent off to Auschwitz, and then the next group of kids took over."