6. Embark On A Journey
After their arrival on Trenzalore, Claras trek begins, quite fittingly, in the catacombs. Catacombs are subterranean burial places, often found under sacred sites. In another call back to Time of Angels Clara echoes the Doctor when she says she hates them. As Clara climbs through the dying TARDIS she is taken on a journey of memory recalling events from the alternate timeline established in Journey to the Centre of the TARDIS. It is here she begins to wake up to her true self, as she relives experiences that were removed from her remembrance. She begins to understand that she is so much more than she once thought. The Doctor is undertaking a journey through the stages of grief. River is gone and he cannot bear to make contact with her echo. He deals with these emotions by denying Rivers importance to his life but her involvement with this quest forces him to confront the fact of her death. River is attempting to ascend to the next level of existence. Her afterlife is not truly that it is a kind of purgatory a place of endless waiting. Her connection to the Doctor has kept her tethered to this reality though she cannot participate fully within it. By speaking the Doctors name she is letting go of his last hold on her, preparing herself to move on. Moffat has left it open, however, as to what River will become. Her final word spoilers was open-ended she could have been trying to reassure the Doctor that Clara was alive, but its also possible to take that as an indication that we havent seen the last of River Song.