When humans are born, they are incredibly vulnerable and they have to be taken care of for a long time before they can fend for themselves. A baby is really without the capability of making it in this world without somebody nurturing it and raising it and teaching it. Now slowly that baby, over the course of time, goes from vulnerability to being able to take care of itself. And there is a change in that being. It learns that not everybody is its mother and not everybody is going to be nurturing towards it. So, slowly defense mechanisms are built up in that baby. It learns to defend itself in the world.