rectangle is an instance of
Object class. However, Object does not have
width attributes, and does not have,
When we define an object instance, we create in essence a new class of object once we begin assigning custom properties and methods. This will come up, so don't let it segue you just now.
The object is a sort of closure on its variables and methods. Only the rectangle instance may invoke its methods. It is the owner of those methods, exclusively. They cannot be called directly, and neither can any other object call it. Think of closure as being beneficial, and more will unfold as you progress through this and next unit.