I just read a great quote about this in an Italo Calvino novel:

"If I think I must write `one` book, all the problems of how this book should be and how it should not be block me and keep me from going forward. If, on the contrary, I think that I am writing a whole library, I feel suddenly lightened: I know that whatever I write will be integrated, contradicted, balanced, amplified, buried by the hundreds of volumes that remain for me to write"