One theme that is enhanced by the elements of fiction in "Cathedral" is how individuals can overcome the condition of what is and enter into a condition of what can be. The transformative quality within individuals is possible through being able to appreciate the mystical qualities of being in the world. This is seen in the narrator when he says, "It's really something." The ambiguous quality of this bit of dialogue helps to establish how individuals who are mired in the most hopeless of situations can be privy to powerful transformations, enabling them to see what can be out of the shards of what is if they are open to such change.
The trajectory of the plot in "Cathedral" also helps to enhance this theme of change. At the beginning of the evening, the narrator is not in such a position. Yet, by the end of the evening, it becomes clear that the narrator has found some path out of the alienation that had gripped him for so long. In being able to share a moment with Robert, there is the possibility for hope and for transformation within a world where existence is defined by the most rigid of contexts.