White Raven is an opera in five acts and three knee plays, for soloists, choir and orchestra, composed in 1991 by Philip Glass in collaboration with Robert Wilson, with libretto by Luísa Costa Gomes.

When contacted in the early 1990s by António Mega Ferreira, member of the Portuguese Commission and future Expo '98 Commissioner, Glass, who had just written The Voyage to celebrate the 500th anniversary of the arrival of Christopher Columbus in America, initially shows no enthusiasm for the idea of redoing an opera on the theme of discovery.

The libretto presents a sort of panorama of characters and events by mixing poetic verses with scientific treatises, newspaper headlines or, as in the finale, a long list of Portuguese historical figures.

It's amazing how by adding just a little complexity here and there to his mind-massaging music -- breaking up foursquare rhythmic repetitions with asymmetrical patterns and nudging syncopations, or surprising us with a jarring bass line that adds a dissonant ripple to the tranquil pool of diatonic harmony – Mr. Glass can suddenly perk up your ears.

The stage is soon populated by a whole roster of weird characters: Africans with garishly painted bodies, one of whom has a huge elephant foot; exotic birds and animals; a sad-faced Dog Man; a spindly dragon; a Miss Universe character in sequined black singing arias on a crescent moon; and a galumphing Tin Man who could have stepped out of a Robert Wilson production of The Wizard of Oz.

The libretto in Portuguese by the writer Luisa Costa Gomes is a cut-and-paste assemblage of philosophical ruminations, historical and epic texts, travel logs, journals and newspaper headlines.