An old man is teaching his grandson about life.
"A fight is going on inside me," he said to the boy. "It is a terrible fight, and it is between two wolves. One wolf is evil. He is anger, envy, sorrow, regret, greed, arrogance, self-pity, guilt, resentment, inferiority, lies, false pride, superiority, and ego. The other wolf is good. He is joy, peace, love, hope, serenity, humility, kindness, benevolence, empathy, generosity, truth, compassion, and faith. This same fight is going on inside you - and inside every other person, too."
The grandson thought about it for a minute and then asked his grandfather, "Which wolf will win?"
The old man replied simply, "The one you feed."
–Wendy Mass, Jeremy Fink and the Meaning of Life