I believe it was Bjarne Stroustrup who said that programming is the art of writing libraries and then using them. After two decades of programming, this still holds true for me. The best way to handle complexity is to write and verify layers with a well defined API, to be used in the layer above it, much in the same way the protocols in the TCP/IP stack are built on top of each other. Once a layer is verified, you can flush the complexity it encapsulates from your brain and focus on the layer above it.
