The difference in style between 'Lohengrin' and 'Das Rheingold' is so very marked that it is only natural to look for some explanation of the sudden change other than the natural development of the composer's genius. Wagner's social position at this point in his career may have reacted to a certain extent upon his music. An exile from his country, his works tabooed in every theatre, he might well be pardoned if he felt that all chance of a career as a popular composer was over for him, and decided for the future to write for himself alone. This may explain the complete renunciation of the past which appears in 'Das Rheingold,' the total severance from the Italian tradition which lingers in the pages of 'Lohengrin,' and the brilliant unfolding of a new scheme of lyric drama planned upon a scale of unexampled magnificence and elaboration. Intimately as Wagner's theory of the proper scope of music drama is connected with the system of guiding themes which he elaborated, it need hardly be said that he was very far from being the first to recognise the importance of their use in music. There are several instances of guiding themes in Bach. Beethoven, too, and even Gretry used them occasionally with admirable effect. But before Wagner's day they had been employed with caution, not to say timidity. He was the first to realise their full poetic possibility. 'Das Rheingold,' the first work in which Wagner put his matured musical equipment to the proof, is the first division of a gigantic tetralogy, 'Der Ring des Nibelungen,' The composition of this mighty work extended over a long period of years. It was often interrupted, and as often recommenced. In its completed form it was performed for the first time at the opening of the Festspielhaus at Bayreuth in 1876, but the first two divisions of the work, 'Das Rheingold' and 'Die Walkuere,' had already been given at Munich, in 1869 and 1870 respectively. It will be most convenient in this place to treat 'Der Ring des Nibelungen' as a complete work, although 'Tristan und Isolde' and 'Die Meistersinger' were written and performed before 'Siegfried' and 'Goetterdaemmerung.'