Wagner's "romantic operas". They reinforced the reputation, among the public in Germany and beyond, that Wagner had begun to establish with Rienzi. Although distancing himself from the style of these operas from 1849 onwards, he nevertheless reworked both Der fliegende Holländer and Tannhäuser on several occasions. These three operas are considered to represent a significant developmental stage in Wagner's musical and operatic maturity as regards thematic handling, portrayal of emotions and orchestration. They are the earliest works included in the Bayreuth canon, the mature operas that Cosima staged at the Bayreuth Festival after Wagner's death in accordance with his wishes. All three (including the differing versions of Der fliegende Holländer and Tannhäuser) continue to be regularly performed throughout the world, and have been frequently recorded. They were also the operas by which his fame spread during his lifetime. "Music dramas" (1851–1882) Starting the Ring Wagner's late dramas are considered his masterpieces. Der Ring des Nibelungen, commonly referred to as the Ring or "Ring cycle", is a set of four operas based loosely on figures and elements of Germanic mythology—particularly from the later Norse mythology—notably the Old Norse Poetic Edda and Volsunga Saga, and the Middle High German Nibelungenlied. Wagner specifically developed the libretti for these operas according to his interpretation of Stabreim, highly alliterative rhyming verse-pairs used in old Germanic poetry. They were also influenced by Wagner's concepts of ancient Greek drama, in which tetralogies were a component of Athenian festivals, and which he had amply discussed in his essay "Oper und Drama". The first two components of the Ring cycle were Das Rheingold (The Rhinegold), which was completed in 1854, and Die Walküre (The Valkyrie), which was finished in 1856. In Das Rheingold, with its "relentlessly talky 'realism' [and] the absence of lyrical 'numbers, Wagner came very close to the musical ideals of his 1849–1851 essays. Die Walküre, which contains what is virtually a traditional aria (Siegmund's Winterstürme in the first act), and the quasi-choral appearance of the Valkyries themselves, shows more "operatic" traits, but has been assessed by Barry Millington as "the music drama that most satisfactorily embodies the theoretical principles of 'Oper und Drama'... A thoroughgoing synthesis of poetry and music is achieved without any notable sacrifice in musical expression." Tristan und Isolde and Die Meistersinger While composing the opera Siegfried, the third part of the Ring cycle, Wagner interrupted work on it and between 1857 and