This quote:
“Inside each of us, there is the seed of both good and evil. It's a constant struggle as to which one will win. And one cannot exist without the other.”

It always reminds me of the following story:
An old Cherokee 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 is evil – he is anger, envy, sorrow, regret, greed, arrogance, self-pity, guilt, resentment, inferiority, lies, false pride, superiority, and ego.” He continued, “The other is good – he is joy, peace, love, hope, serenity, humility, kindness, benevolence, empathy, generosity, truth, compassion, and faith. The 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 Cherokee simply replied, “The one you feed.”