-  Abstraction and Encapsulation
      - What are they?
      - are they not common principles which you have been using in real life?
         haven't you used these two principles in building your programs?
       -  how do they manifest in an object oriented process?
 

      Reading 1: Chapter "Abstraction Descant" from Richard Gabriel's book on
                                Patterns of Software
       Reading 2: part of Alan Snyder's 1986 OOPSLA paper on Encapsulation
                                and Inheritance