At times, opera can also be the art of nostalgia and of longing, referring not just to the voices. Liceu has once again restaged in its scene its own production of L’elisir d’amore, one of the most successful productions of the theatre, which has toured around bringing dignity to Liceu’s name.  The staging is signed by Mario Gas as stage director, who started his relationship with this title over 30 years ago. That production was the grandmother of the one...