One of the earmarks of the progression of music by George Gershwin and Richard Rodgers was their ability to fuse vocal music with concepts found in classical, symphonic music (including ballet). Much as Ludwig van Beethoven had crossed the line from pure symphonic music to a fusion of symphonic and vocal music in his towering 9th Symphony, Broadway composers were about to take the same step forward, as they wrote scores that relied more heavily on classical forms. The art form was progressing.
It was inevitable that, as the the written word turned toward more substantial subject matter, the music would have to enter a period of greater substance. It was also inevitable that, as the music found its own stature, both music and word would sense an opportunity to achieve a higher purpose. How does one explain Gershwin’s transformation in a matter of eight years from the light frivolity of Funny Face (1927.59) to the deadly serious music of Porgy and Bess (1935.13)? At the same time, we should also ask ourselves whether Gershwin would have been physically and mentally capable of writing Porgy and Bess, unless he had first composed Rhapsody in Blue, Concerto in F and An American in Paris?