"Performing an act of kindness is a tonic for the one who performs it. It is a cornerstone of my faith that, just as our bodies are made so that certain foods and certain habits are healthy and others are unhealthy, so are our souls made so that certain kinds of behavior nourish the soul and other kinds are toxic. Human beings were fashioned to be friendly, honest, and helpful to each other. When we act that way, when we resist temptation, when we go out of our way to do a favor for someone, we feel right. Something inside us says, 'Yes, this is the way a person is meant to feel.' When we are deceitful or jealous, we are acting against our nature, and we have to work hard to resist the message our bodies and souls try to send us. . .
"Why did God create the world and fill it with such erratic, unpredictable creatures as we human being are? One Jewish tradition would have it that God made the world the way it is so that we would have the possibility of being nice to each other. The Talmud teaches that when a person does a good deed when he or she didn't have to, God looks down and smiles and says, 'For this moment alone, it was worth creating the world.'
"When we go out of our way to be kind to someone, in large ways or small, our reward is the knowledge that we have redeemed the world.” (Rabbi Harold Kushner, in the foreword)