On the other hand, understanding what part of what you are doing is due to a leak from the lower layer helps you isolate it in case you should shift what you ar

On the other hand, understanding what part of what you are doing is due to a leak from the lower layer helps you isolate it in case you should shift what you are building on. And now we have another abstraction! It is rare that you need to understand more than a few layers down, at any given time. As I type on this keyboard, I have no care what the neutrons, protons and electrons are doing in the keys are doing. From time to time maybe if I get a nasty static electric shock I want to stop.