This is a gem of a post. Loved it.

Don't miss:

   Notice how the fish interlock without leaving out any space in between them.
   Escher FTW.

And:

   Abstraction barriers are useful tools that can reduce the cognitive overhead
   on the programmer.

Although of course familiar with the concepts of abstract data types from CS and architecture/implementation layers from CompE/EE, I've not heard the term abstraction barriers before this. I like the combination.