All those are great examples of things on different abstraction layers. I agree with you insofar as you can't know what you're building ahead of time so writin

All those are great examples of things on different abstraction layers. I agree with you insofar as you can't know what you're building ahead of time so writing software is continuous process of revision, but it's still the case that when I'm writing a particular piece of code I can ask myself what is actually on this layer vs not on this layer, and write my code accordingly.