This very same concept is expressed in different formats across different cultures such as the angel and devil in cartoons, the Holy Spirit and the Ego in Christianism or the Higher Self (or Buddha nature) and Lower Self (or Ego) in Buddhism-Yoga traditions.
The following is one of my favourite stories. I think it beautifully illustrates the dilemma that we all face, regardless of how much inner work we have done or how mindful we are.
A Cherokee Parable
As an old Cherokee is sitting with his grandson by a campfire, he decides to teach him a lesson about life. And so he says to the boy:
“A battle is going on inside me. It is a terrible fight between two wolves.”
He continued:
“One wolf is evil – in his heart lies nothing but anger, envy, greed, arrogance, resentment, self-pity, ego and lies. But the other wolf is good. His heart contains joy, peace, hope, humility, kindness, empathy, truth and above all love.”
The elder went on to explain that these two wolves fight inside each and every human being.
The grandson thought about this for a minute. Then, intrigued, he asked his grandfather:
“Which wolf is going to win?”
The old man simply replied:
“Whichever one you feed.”
How Mindfulness Empowers Us: An Animation Narrated by Sharon Salzberg – 2 min video