The organ is one of the oldest musical instruments. But it wasn’t until 1822 that the German instrument maker Christian Buschmann managed to combine the principle of a reed-organ with a portable keyboard and its own set of bellows to create the accordion: an instrument loved by the masses but also able to hold its own in classical music. A true people’s instrument, the accordion quickly became popular in eastern Europe, and the Soviets established the world’s first conservatory accordion course in Kiev in 1927. Like a portable organ, the accordion can provide both melody and rich harmony, and today, virtuoso accordionists like Ksenija Sidorova are capable of feats as dazzling as any superstar pianist. Kurt Weill introduced the accordion into his 1930 opera Rise and Fall of the City of Mahagonny; more recently the jazz musician Uri Caine reinvented Wagner, with the accordion taking the place of an orchestral wind section. But while the accordion has become part of the palette of the contemporary orchestral composer, it still feels most at home at the intersection of jazz, classical, and folk traditions. The tangos of Astór Piazzolla would be unthinkable without the sound of the accordion’s mighty South American cousin, the bandoneon.