I think that both narratives are vital to the story's themes. Ruth tells James that his father Andrew McBride, a reverend, was a man with "vision". She sighs and then states that the times are different. Circumstances are different; they make for different men. It is hard to find a good minister with "vision" these days, according to Ruth. She states that it has something to do with "foresight", and James admits to his mother that he does not have it.
The irony is that while memoir-writing and the act of "remembering" constitute a journey back in time, what is found there generates a possible source of new strength. Crucial to any idea of the future, the remembered history becomes a part of a person's identity, adds depth to the experience of living, and serves as a link between the present and the future. While James may not have the kind of "vision" that Ruth admires, he has the kind that is, perhaps, the necessary starting place for any fresh imagining of the future.