Hierarchy is a kind of order of abstractions.
The function of good software is to make the complex appear to be simple.
All of life is iterative. It goes back to the point I made earlier, which is you can't a priori know enough to even ask the right questions.
C++ also supports the notion of friends: cooperative classes that are permitted to see each other's private parts.
Ah, but who do you think created the chaos?
The amateur software engineer is always in search of magic.