Feed the white dog

There is a story in Native American history of an Indian chief who one night talking to his tribe tells them there are two dogs inside his mind. One a white dog who is good and courageous, the other a black dog who is vengeful and spiteful. He tells the tribe the dogs are fighting to the death. A brave, not able to wait for the end of the story asks "Which one of them will win?" The chief responds "The one I feed."