[Symmetry]

One should always try to write well modularized code with lots of good abstraction barriers so that you only ever have to have a fraction of the complexity of the system in your head at a time. If you had to understand everything down to the transistor level you could never even understand a Hello World program. That's because the language you use gives you good abstractions so you don't have to worry about linking, operating systems, memory allocation, etc. When writing complex systems you should strive to create such good abstractions yourself.