'Mi raccomando brevità, e fuoco,' is how Verdi illustrated his blueprint for Ernani to his librettist Piave. He can't have been disappointed by the final product. Verdi's fifth opera brims with rollicking tunes, stirring arias and incendiary ensemble numbers -- it is an uninterrupted flow of musical invention. Such has not secured Ernani regular appearances at La Scala. The opera had last appeared at the Milan house 32 years ago, in a production from Luca Ronconi...