This song, by Billy Joel, is about perhaps the most fundamental truth about human existence that there is: that we are all stuck in our own perceptions. We can only see things through our own eyes, which are inherently different from any other person’s eyes, literally and figuratively.
In the literal sense, think about sitting in a room with a crowd of people, and looking at the same object. Each person comes from a different angle and so each person, in essence, sees a different object. Now, apply that concept to an intangible idea, only the angle our vision is coming from is based on each of our unique experiences.
No two people have been doing the same exact things, seeing objects from the same angle for their whole lives, and so each person has his or her own perception.
Joel’s “Summer Highland Falls” tells of this isolating concept through an idea of two people fighting. They cannot see each other’s points of views, and so that is exactly what causes the disagreement as well as why it’s so hard to resolve it.
With the line, “For all our mutual experience, our separate conclusions are the same,” he suggests that each person is, at her core, the same, save for every single thing that shapes us (So not really the same at all). But, we respond and formulate our persons in the same ways. We are all the same in that we are different.
The line that I like most is, “Now we are forced to recognize our inhumanity. Our reason coexists with our insanity.” It goes to show that all of our reasoning, all these things that we build our reality upon, is merely part of our contrived perception. We are all living in our own worlds, which is where insanity lies.