In the surfeit of power I was a murderer and an oppressor . In my most evil moments I was convinced that I was doing good , and I was well supplied with systematic arguments . It was only when I lay there on rotting prison straw that I sensed within myself the first stirrings of good . Gradually it was disclosed to me that the line separating good and evil passes not through states , nor between classes , nor between political parties either - but right through every human heart - and through all human hearts ... .

Select from: (I) They had a cellmate who encouraged them to take a good hard look at their past conduct. (II) The prison offered a spirituality course that allowed them to think about the philosophy of the matter. (III) They spent much time praying to god and had a vision outlining what they had done wrong. (IV) The humbling experience of losing all freedom was an eye opening paradigm shift for the speaker.
Q: Why did being imprisoned prompt the speaker to reflect on and realize the true nature of morality ?
(IV)