Toward the end of the story, the blind man asks the narrator to describe a cathedral. Why is the narrator unable to do so? What does his inability to do so reveal about him?

I think the narrator is transfixed by something in the blind man. It is no longer the narrator's interpretation of the cathedral at play but the blind man's. The experience is life changing, it is like a different time and space. I'm not sure he wants to draw his own cathedral at this point, he freely gives over to the blind man.