In the original timeline, in contrast with Marty's shy and unassertive father, George McFly, Doc is a supportive and open-minded mentor for Marty. Doc's positive influence in turn allows Marty to mentor George in 1955, which appears to encourage George's later success as a novelist, and help him become a better husband and father. One line in particular, "If you put your mind to it, you can accomplish anything", originates from Doc. Marty repeats it to George in 1955, who repeats it back to Marty in the post time travel 1985.