| Quote #1
Harper: People who are lonely, people left alone, sit talking nonsense to the air, imagining... beautiful systems dying, old orders spiraling apart... (1.3.62)
Every character in the play is isolated in some way. Harper definitely has a pretty bad case of it, though. The distance between her and her husband, Joe, is so great that she has to create imaginary friends and worlds to hang out in.
| Quote #2
Harper: This is the very threshold of revelation sometimes. You can see things... how sick you are. Do you see anything about me?
Harper and Prior both become more and more isolated as the play progresses. By the end they are both abandoned by their romantic partners. In this scene they meet each other in a shared dream, though they've never met in "real" life. It's like for a moment, in their dreams at least, they aren't quite so isolated.
| Quote #3
Louis: It's not really a family, the Reagans, I read People, there aren't any connections there, no love, they don't ever even speak to each other except through their agents. [...] I think we all know what that's like. Nowadays. No connections. No responsibilities. All of us... falling through the cracks that separate what we owe to ourselves and... and what we owe to love. (2.7.31)
Here Louis seems to use the dysfunction of the Reagan family as a metaphor for the isolation that we all sometimes experience. We're guessing that Louis is getting all reflective here because he still feels horribly guilty about leaving Prior. Abandoning his lover has made him feel totally isolated and has led him to think about the isolation all around him.