From the Preface, and on the cover:

"When I realized that I was actually going to make a movie out of the novel ‘The Godfather,' I sat down and began to read the book again, very carefully, my pencil poised. Upon that second reading, much of the book fell away in my mind, revealing a story that was a metaphor for American Capitalism in the tale of a great king with three sons: the oldest was given his passion and aggressiveness; the second his sweet nature and childlike qualities; and the third, his intelligence, cunning and coldness.”