3/4. Maria Callas. Violinist Isabelle van Keulen explains to Tom Robinson why Maria Callas is such an inspiration to her. Highlights from Callas's operatic roles include Carmen and Medea, and Donna Leonora from La Forza del Destino. Plus a selection of telling exchanges from recordings of Callas's masterclasses at the Juilliard School in New York. Producer Alan Hall