Once he had decided on the value of a new work he was determined to program it, regardless of whether it was long, abstruse, dissonant, difficult to perform, or difficult to comprehend. Often he arranged for the major portion of the week’s rehearsal time to be devoted to perfecting the orchestra’s interpretation of the new work.
This according to “Serge Koussevitzky and the American composer” by Aaron Copland (The musical quarterly XXX/3 [July 1944] pp. 255–269); an appendix lists 123 American works that he programmed during his first 20 years in Boston.
Today is Koussevitsky’s 140th birthday! Below, his recording of Copland’s Appalachian spring.