Whenever I go for a walk, my feet each claim credit for any forward momentum. My right foot says it has all the initiative and is the real driver for my progress. It sometimes complains that my left foot just tags along, not doing the heavy lifting.
My left foot replies that it plans where we should go and without its direction the right foot would carry me off randomly. My left foot also seems to care about the welfare of my right foot. My right foot is self-interested.