The viola is only slightly larger than the violin but possesses a middle range that is richly expressive and full of pathos. It has been played by some of the greatest composers, including J.S. Bach, Mozart, Beethoven and Dvořák—and the rise of virtuoso players in the 19th century encouraged composers to write ever more expressive works for the instrument, not least sonatas and concertos, such as those in this collection. The explosion of pieces written for it in the 20th century has ensured that the viola can now take centre stage in the world’s concert halls.