If you would like to describe Law of Demeter in one sentence, it would go like that: “talk only with your (closest) friends”.
In full form it tells that a method of particular object can call only methods that belong to:
the same object,
any object that is an attribute of this object,
any object that was passed as a method’s parameter
Some time ago I wrote about objects' attributes. Parts that identify them. However, the objects are exactly like us - it’s our behavior that determines who we are, makes us who we are. This behavior and reactions are the things that really interest others. Would Sebastian be the same annoying person if his name were different? Assuming there's no magical power in our names he probably would.
Don't get me wrong, I don't want to minimise the importance of object's attributes. The behavior of the object often depends on them, e.g. if the age is one of person’s attributes, it's clear that it determines many activities that the person can or cannot do.