One Ring to rule them all, One Ring to find them, One Ring to bring them all and in the darkness bind them.
—John Ronald Reuel Tolkien
General propositions do not decide concrete cases.
—Oliver Wendell Holmes
A philosopher of imposing stature doesn’t think in a vacuum. Even his most abstract ideas are, to some extent, conditioned by what is or is not known in the time when he lives.
—Alfred North Whitehead
Why art thou cast down, O my soul?
In this chapter you’ll learn:
• The concept of polymorphism.
• To use overridden methods to effect polymorphism.
• To distinguish between abstract and concrete classes.
• To declare abstract methods to create abstract classes. ...