Author's Notes:
For purposes of fiction, I've invented Thomas Vaughn Voight, the supposed existentialist expert, but Anita Brookner and the quotation cited from her that are real. I've studied a lot of existentialist literature in my time and recently reread Sartre's Existentialism is a Humanism. It seems to me that most of the common perception of existentialism is wrapped up with the idea of despair (per Albert Camus) but frankly I see Sartre as much more optimistic and liberating than that. As I watch more Doctor Who, it occurs to me how much the philosophy fits the Doctor. As to the discussion of the presence of God, I won't take a stand on that, but I think it's clear where the Doctor stands, and this seems reasonable to me for Rose's perspective.