I thought the film’s use of the theme was much more politicized than the book’s. In the book, when Kenny says that he and George are invisible, I wasn’t quite sure what he meant.
In the movie, invisibility has been threaded throughout much more explicitly: in the classroom scene George clearly describes “invisible minorities” to his class. I took this as the filmmaker’s attempt to make the historical particularities of George’s situation clear.
In the book, however, Kenny’s comment sort of complicates George’s understanding of his own minority position. Throughout the book, George believes his pain is invisible to others because society has refused to acknowledge his relationship.
He thinks this is a somewhat unique situation, because of his position as a gay man in a homophobic society. Kenny’s comment, however, suggests that invisibility is more inclusive than that.
Perhaps Kenny means that they’re invisible because they’re out when no one expects them to be out, or because their homosocial behavior isn’t understood by society, or because they’re powerless to stop the Cuban Missile Crisis. Or, perhaps Kenny knows that George is gay and is trying to have an experience by sharing the evening with him.
I don’t know and I don’t think we’re supposed to know. One of the fantastic things about this novel for me is the way it explodes the idea that we grow closer to others by understanding them better. Caring, closeness, and love in the novel aren’t degraded by failures of understanding.