public class Forum
{
	public static void sayIt(Speaker s)
	{
		s.speak();
	}
	
	public static void main(String[] args)
	{
			
		Speaker current;
		current = new Philosopher();
		current.speak();
		current = new Professor();
		current.speak();
		sayIt(current);  // the same thing as above
		
		//current.pontificate(); //compile error
		
		// Use a cast 
		((Professor)current).pontificate();
	}
}