http://www.religioustolerance.org/rel_hate.htm
A man told his grandson: "A terrible fight is going on inside me -- a fight between two wolves. One is evil, and represents hate, anger, arrogance, intolerance, and superiority . The other is good, and represents joy, peace, love, tolerance, understanding, humility, kindness, empathy, generosity, and compassion. This same fight is going on inside you, inside every other person too."
The grandson then asked: "Which wolf will win?"
The old man replied simply: "The one you feed."