Employee homer = new Employee();

homer is a variable that can store
the location of an Employee. *LEGAL*

Marketer mark = new Marketer();

mark is a variable that can store
the location of a Marketer. *LEGAL*

Employee sam = new Marketer();

sam is a variable that can store
the location of an Employee. *LEGAL*

   Why?
   - sam can store the location
     of an Employee
   - All Marketers are Employees
   - OK

Lawyer lenny = new Employee(); *NOT LEGAL*

   Why?
   - All lawyers are employees
   - Not all employees are lawyers
   - we're trying to make lenny
     store the location of an employee who
     isn't a lawyer