Why does Gatsby frame his life after Ben Franklin? And where in the book does it say this?
Ben Franklin in his Autobiography sets up a plan to achieve moral perfection. In the plan, Franklin makes a list of vices he wishes to eliminate and sets up a 13 week plan where he hopes to eliminate them one by one. Franklin discovers the task is far more difficult than he imagined, and eventually abandons the plan.
Jay Gatsby wants to achieve a different type of perfection as well. He wants to seem to the outside world to be a gentleman and remove himself as far as possible from his working class roots. He, too, sets up a plan for himself and his schedule and resolves echo Franklin's. We are told about this in the last chapter of the novel (chapter 9) by Gatsby's father when he comes for the funeral.
Gatsby, like Ben Franklin, is the quintessential self-made man. Like any great American, they both set goals for themselves and then (with hard work and fortitude) they achieve them. Whether it is “a penny saved…” or “no chewing,” greatness comes from endurance, and focus: the “can-do” spirit. They both exemplify the “rags to riches” scenario that is so American. They believe in the power of the individual and the power of holding on to dreams. In the last chapter of the book, Gatsby’s father shows Nick Gatsby’s Hop-a-Long Cassidy book with his goals written in the back. These goals mirror (if not down-right copy) Benjamin Franklin’s goals from his autobiography.
Gatsby models his life after Franklin because Franklin is the first major figure in American history to engage in methodical reconstruction of his personal identity. He kept journals and tracked how well he lived by the values he set for himself.
This is discussed in the book's final chapter.