In "Cathedral", what does Robert "see" over the course of the evening?

Robert can see much the narrator cannot.  The narrator was very close-minded and did not want Robert to visit.  Robert, through his other senses, is able to "see" things.  He can trace the outlines of someone's face, for example, and picture his or her face in his mind.  That night, after the narrator's wife leaves the room and the men are alone together, the narrator has turned on the TV and is trying to describe what he sees to Robert. When a cathedral is on the screen, however, the narrator has difficulty describing it, so Robert asks him to draw it for him.  He does, but then Robert asks the narrator to draw it with his eyes closed, which provides the narrator with a completely different perspective about Robert:

At this moment, something strange happens to the narrator. ''It was like nothing else in my life up to now,’’ he tells the reader. Even when Robert tells him to open his eyes, he keeps them closed. Something has happened to him that has changed his understanding of life. ‘‘My eyes were still closed. I was in my house. I knew that. But I didn't feel like I was inside anything.’’ No longer hostile to Robert, no longer aware of Robert's blindness, the narrator experiences the possibility of change in his life.