Pianist Kirill Gerstein chooses the conductor and composer Ferruccio Busoni. Matthew Parris presents.

When Busoni died in Berlin in 1924, his pupil Kurt Weill said, "We did not lose a human being but a value."

Unravelling exactly what this means is the pianist Kirill Gerstein, a great admirer of Busoni and also a performer of his work. Busoni was a thinker as well as a composer. His book from 1907, Sketch of a New Esthetic of Music, has influenced generations of musicians.

With contributions from Erinn Knyt and Anthony Beaumont

Producer: Miles Warde.

First broadcast on BBC Radio 4 in 2019.