Starting from the left you can see that it is quite dark..but within inches away (on the right), it is very bright. The bridge seems to separate the two lights: darkness and light. To me it is a very symbolic picture of how people walk along this bridge every day and things are coming at them from every angle forcing them to make choices of whether to do what is right or to do what is wrong. We can easily turn either to the left or right. Whether we want to believe it or not, every decision we make will either make this world a better place or worse off.