Marius Casadesus was a well-known violinist and a composer, also known for instrument building. Marius Robert Max Casadesus was part of a remarkable musical family of Catalan descent. His father, Luis Casadesus was born in Figueras, Spain, and migrated to France where he married Mathilde Sénéchal. Luis was a typographer by day and a café musician by night, playing violin, guitar, and mandolin. He wrote an important guitar method. He had nine children: Francis, Rose, Robert, Henri, Jeanne, Marcel, Cécile, Régina, and Marius, and taught them all music. All but Jeanne became professional musicians. The most famous member of the family Robert (1899 - 1972), one of history's great pianists, was the son of Marius' brother Robert (1878 - 1940), a singer, actor and composer, while conductor Jean-Claude Casadesus (b. 1935) is a grandson of Marius' brother Henri (1879 - 1947). Marius was given a musical education by his parents and by his older sister, Rose, a pianist. He entered the Paris Conservatory and won first prize in violin in his graduation year, 1914. He began an international touring career, often accompanied by nephew Robert at the piano. He premiered Maurice Ravel's bravura violin composition Tzigane in the presence of the composer in Barcelona. He founded the Marius Casadesus String Quartet. He joined the Société des Instruments Anciens Casadesus then helped found its successor, the Société Nouvelle des Instruments Anciens and thus was one of the earliest advocates of what is now known as the "original instruments" or "period instruments" movement. In 1954, he also founded the ensemble Violes et Violons, devoted to recapturing the authentic timbre of string instruments appropriate for the music of any particular epoch. The many rare and old instruments he collected are housed in the museum of the Boston Symphony Orchestra. Marius was also a luthier who made various replica instruments. These included not only instruments of the viol and violin families, but also guitars, mandolins, and such unusual old instruments as the quinton and the descant gamba. These instruments may be found in such institutions as the library of the Opéra de Paris, the Versailles Chateau Museum, and the headquarters of the authors' rights organization SACEM. He was also a composer, mainly of orchestral and chamber music. These include a Symphony for orchestra of violins (1951) and several works with violin or cello solos. Marius and his brothers Francis and Henri all wrote compositions in the spirit of older composers and, in the same manner as the famous violinist Fritz Kreisler, presented them as "rediscoveries" of works by old masters such as C.P.E. and J.C. Bach and Handel, or so the stylistic evidence suggests. (Moreover, the Casadesus family has never denied that the works are by the three brothers.) In 1931, a work appeared, identified as a violin concerto written by Wolfgang Mozart at age ten and "edited and orchestrated" by Marius Casadesus. It was premiered in 1931 at a Lamoureux Concert and was recorded by the young Yehudi Menuhin. This concerto was called "Concerto for Princess Adelaide" or simply the "Adelaide Concerto" and had currency for a while, though scholars became suspicious of its origin when Marius did not produce any of the original documentation necessarily lying behind his edition if the work were genuine. In 1977, in a court case concerning whether Marius actually had authorship rights in the published "orchestration" he testified that he had, after all, written the work in its entirety. In 1962, Marius Casadesus was made a Commander of the Legion of Honor. He had three children, Mathilde, Martine, and Gréco.