Polymorphism may be considered the “great enabler” of OOP. Polymorphism enables programmers to manipulate subclass objects using superclass references. This advantage may seem insignificant until one considers that mom physical systems consist of collections of objects. A power system for example, consists of a collection of components that may, in a very general sense, be considered objects of some abstract class called PowerSystemObject. Looked at more closely, each object can be said to hail from a more specific subclass