Who said "A composer's work is never really finished."?

This quote is attributed to George Gershwin.

A composer's work is never really finished. - George Gershwin

"A composer's work is never really finished."

George Gershwin

Jazz Composer Pianist American 1898–1937

"Life is a lot like jazz - it's better when you improvise"

"I frequently hear music in the very heart of noise"

"The real American folk song is a rag"

"True music must repeat the thought and inspirations of the people and the time"