from simple to complex

I am fascinated by how a few simple lines become complex very quickly when overlapped.
Cities we live in are like this in some respect.  Roadway grids, utility lines, water body, vegetation...they all overlap.  As independent entities, each are sometimes consciously related, sometimes accidentally related, sometimes miss each other intentionally or by chance, sometimes brutally unrelated. 
...in a much more multifaceted manner than just a few lines, of course.