Symphony No. 5 was premiered in Helsinki to great acclaim by Sibelius himself on 8 December 1915, his 50th birthday. The version most commonly performed today is the final revision, consisting of three movements, presented in 1919. The Fifth is Sibelius's only symphony in a major key throughout. From its soft opening played by the horns, the work develops into rotational repetitions of its various themes with considerable transformations, building up to the trumpeted swan hymn in the final movement. While the Fifth had already started to veer away from the sonata form, the Sixth, conducted by the composer at its premiere in February 1923, is even further removed from the traditional norms. Tawaststjerna comments that "the [finale's] structure follows no familiar pattern". Composed in the Dorian mode, it draws on some of the themes developed while Sibelius was working on the Fifth as well as from material intended for a lyrical violin concerto. Now taking a purified approach, Sibelius sought to offer "spring water" rather than cocktails making use of lighter flutes and strings rather than the heavy brass of the Fifth.