We are, after all, social animals.  Without human friendship, without the human smile, our lives become miserable.  The loneliness becomes unbearable.  Such human interdependence is a natural law- that is to say, according to natural law, we depend on others to live.  If under certain circumstances, because something is wrong inside us, our attitude toward our fellow human beings on whom we depend becomes hostile, how can we  hope to attain peace of mind or a happy life?  According to basic human nature or natural law, interdependence- giving and receiving affection- is the key to happiness.

-Dalai Lama from The Compassionate Life.