As a pioneer of New Music and one of the greatest pianists of his time, Ferruccio Busoni (1866 - 1924) is one of the most intriguing figures in modern music history. This edition presents, for the first time, all accessible letters that the Italian composer wrote to his Swedish wife Gerda (1862 - 1956), an extraordinary and previously underestimated personality. They provide profound insight into the fruitful mutual complementarity of the two spouses' differing characters. Before the reader's eyes, a subtle portrait of Busoni emerges as a universal personality—pianist, composer, aesthetician, educator, arranger, editor, and writer—while also revealing the richly contradictory human side of the musician. In the light of unadulterated and new sources, a depiction of Busoni becomes visible that significantly differs from the traditional narrative.