Two Wolves

Today my Buddhist podcast ended with a Native American story that I was able to find several places on the Internet, mostly credited as a Cherokee story, although it was occasionally mentioned as Eskimo and once as a George Bernard Shaw quote. The simplest version of it is this:

A Native American grandfather was talking to his grandson about how he felt about a tragedy. He said:
- I feel as if I have two wolves fighting in my heart. One wolf is the vengeful, angry, violent one. The other wolf is the loving, compassionate one.
The grandson asked him:
- Which wolf will win the fight in your heart?
- The one I feed, answered the grandfather.