Comprising four separate operas, Wagner's visionary Der Ring des Nibelungen (The Ring of the Nibelung) took 25 years to complete. Centred around a ring of power and the attempts of various people to acquire it, the Ring cycle explores the relationship between love and earthly power and the themes of yearning and loss, all within a setting of medieval legend. The prologue Das Rheingold deals with the theft and subsequent surrender of the ring forged from the Rhinegold by the Nibelung dwarf Alberich.