Short answers, pulled from the story.
The word guilt first emerged in the Old English language as gylt, meaning crime, sin, fault, fine, or debt, and it was derived from the verb gieldan, which translates to to pay for or debt. By the year 1690, the meaning had shifted to describe a sense of guilt, and the phrase guilt by association would not appear in recorded history until the year 1941.
Sigmund Freud revolutionized the understanding of guilt by rejecting the role of God and instead blaming its existence on the individual's own fear of loss of love and relationships, beginning in childhood. He proposed that a child turns this fear inward to create self-directed anger, a process that forms the superego, the internal conscience that never sleeps.
Neuroscientist Antonio R. Damasio and his colleagues demonstrated that subjects with damage to the ventromedial prefrontal cortex lack the ability to empathically feel their way to moral answers, coldly coming up with end-justifies-the-means answers when confronted with moral dilemmas. Individuals high in psychopathy lack any true sense of guilt or remorse for harm they may have caused others, instead rationalizing their behavior, blaming someone else, or denying it outright.
Some evolutionary psychologists theorize that guilt and shame helped maintain beneficial relationships, such as reciprocal altruism, by reducing the chances of retaliation by members of a tribe and thereby increasing survival prospects. This emotion makes it possible to forgive and helps hold the social group together, serving as a mechanism to deal with conflicts and events in which individuals inadvertently or purposefully harm others.
Guilt in the Christian Bible is not merely an emotional state but also a legal state of deserving punishment, with the Hebrew Bible using a single word to signify sin, the guilt of it, the punishment due unto it, and a sacrifice for it. The New Testament says that forgiveness is given as written in 1 Corinthians 15:3, 4, stating that Christ died for our sins according to the Scriptures, was buried, and was raised on the third day according to the Scriptures.
Cultural anthropologist Ruth Benedict described shame as the result of a violation of cultural or social values while guilt is conjured up internally when one's personal morals are violated. Psychoanalyst Helen Block Lewis stated that the experience of shame is directly about the self, which is the focus of evaluation, whereas in guilt, the self is not the central object of negative evaluation, but rather the thing done is the focus.