Ever Had a Bologna and Potato Chip Sandwich?

At the end of the movie Metropolis, our main man states in a big ol text screen that “The mediator between brain and hands must be the heart”.

It's not the most mysterious of quotes. Without compassion there can't be a relationship between any two or more people. Obviously, in the setting for Metropolis, the big man has no compassion for the little man. He doesn't know or care about what the lower class has to go through, and they rebel. The same goes for any society, and has been mirrored in history multiple times. This obviously cuts said society off at the ankles, and after toppling over, gives the head some time for reflection while it grows it's legs back.