The fourth in a series of programmes in which conductor Leonard Slatkin explores ways of listening with fresh ears to the basic elements of music. Composer Aaron Copland wrote that timbre in music is analogous to colour in painting. How do composers use tone colour? How would the opening of Beethoven's Fifth sound if he had written it for brass? Leonard and the BBC Philharmonic try out alternative orchestrations to various works and end with a complete performance of that masterpiece of tone-colour, Rimsky-Korsakov's Capriccio Espagnol.