Short answers, pulled from the story.
Otto Fenichel published The Psychoanalytic Theory of Neurosis in 1946 to describe how guilt functions as a persistent internal conflict. This work outlines the mechanisms by which guilt operates within the human psyche.
The development into a sense of guilt appeared in 1690 as a variation of original meaning. The term evolved from the Old English form gylt which signified crime, sin, fault, fine, or debt.
Sigmund Freud argued that this feeling stems from a child's fear of losing parental love. He believed the child turns this fear inward to create self-directed anger during early childhood when parents reject the child for perceived misbehavior.
Individuals high in psychopathy lack any true sense of guilt or remorse because they rationalize behavior, blame someone else, or deny it outright. These individuals have little ability to plan ahead for the future and will do whatever it takes to benefit themselves without reservation.
Collective guilt arises among a group when perceived illegitimate harm targets another group. An individual must identify himself as part of the in-group to experience this reaction which produces a perceptual shift from thinking of oneself in terms of I and me to us or we.