I keep getting StackOverFlowException whenever I instantiate an instance of A class. I know it has got something to do with the fact that A.b field is of type derived from class A. But why would that cause an exception?

static void Main(string[] args)
{
     A a = new A(); // exception
}

class A 
{
    private B b = new B();
}

class B:A {}

thank you