 Cardus's verdict, however, is that Delius's chamber and concerto works are largely failures.After 1917, according to Payne, there was a general deterioration in the quantity and quality of Delius's output as illness took hold, although Payne exempts the incidental music to "Hassan" (1920–23) from condemnation, believing it to contain some of Delius's best work.The four-year association with Fenby from 1929 produced two major works, and several smaller pieces often drawn from unpublished music from Delius's early career.