Eugène Ysaÿe’s Sonata for two violins is no less virtuosic than his famous Six Sonatas for solo violin op. 27. The work, which was not published during his lifetime, has a complex genesis: It is based on a trio for two violins and viola, which Ysaÿe reworked into a violin duo in 1915 in order to play it together with Queen Elisabeth of Belgium. The fair copy of the score, made in April 1915, is dedicated to the music-loving ruler, with whom Ysaÿe was on friendly terms. However, the technical demands were too great for a joint performance. For his Henle Urtext edition, editor Ray Iwazumi, who as a virtuoso and scholar is extremely familiar with Ysaÿe’s works, carefully evaluated the numerous autograph sources of both versions. Additionally, he provided fingerings for both parts. Both versions are formatted as performance scores in which the respective other part is found in small print above the other – Queen Elisabeth could not have wished for a better basis for mastering this complex masterpiece! In her preface, Ysaÿe specialist Marie Cornaz presents the latest research on the work’s intricate genesis.