Well, it seems that having a structure is the most fundamental principle. While in reality structures formed and maintained according to the laws of physics, in

Well, it seems that having a structure is the most fundamental principle. While in reality structures formed and maintained according to the laws of physics, in CS we have to explicitly define the rules, which is what Abstract Data Types (which define Interfaces) are. Protocols and Interfaces are mere generalizations of ADTs. There are, however, at least some "laws of the universe" in CS. These are Interrupts (the only way to do I/O right), specialized Syscalls, etc. One should respect them.