A tetralogy literally designates a group of four related works. According to the ancient Greeks, it is a collection of four dramatic plays. In music, the Tetralogy is a direct reference to the work of the German composer Richard Wagner: Der Ring des Nibelungen (The Ring of the Nibelung). The cycle, inspired by Germanic and Norse mythology was the fruit of almost thirty years of research and introspection. The opera is comprised of a “a prologue and three days”: Das Rheingold, Die Walküre, Siegfried and Götterdämmerung. The entire performance of the work takes from thirteen to eighteen hours, depending on the conductor. The Paris Opera presented a French version of the complete cycle for the first time at the Palais Garnier in June 1911. It would be performed in German for the first time in 1955 with Hans Knappertsbusch conducting.