Many see Wagner's 'Tristan und Isolde' as the beginning of the move away from common practice harmony and tonality and consider that it lays the groundwork for the direction of classical music in the 20th century. The Prelude and Liebestod is a concert version of the overture and Isolde's Act 3 aria 'Mild und leise'. The arrangement was by Wagner himself, and it was first performed in 1862, several years before the premiere of the complete opera in 1865. The Liebestod can be performed either in a purely orchestral version, or with a soprano singing Isolde's vision of Tristan resurrected.