Ring of the Nibelung, The, is a cycle of four operas by the German composer Richard Wagner (see Wagner, Richard). Its title in German is Der Ring des Nibelungen. The Ring cycle is one of the greatest stage spectacles in opera, with a musical score that requires a large orchestra containing instruments that were Wagner's own inventions, notably the Wagner tuba and the stierhorn, an instrument modeled on the ancient cow horn. Recurring themes in the music, called leitmotifs, depict certain characters and concepts. Wagner wrote the libretto (text) himself, in German, basing the story on the ancient German poem Das Nibleungenlied and on Teutonic mythology.