I did some research on Joseph Schmidt. He was a Jewish person living in wartime Germany. Here is a great article showing his struggles in that dreadful time. www.operanostalgia.be/html/Schmidt2.html
SIN DUDA LA SUPERIORIDAD DE FRITZ ES INDISCUTIBLE MUCHO MAS MUSICAL GUSTO PARA CANTAR UNA VOZ MAS HOMOGENEA BELLEZA EN COLOR Y ESTUPENDA TESITURA DIFICIL COMPARARLO