Final answer:
The statement on Chillingworth's role reveals his transition from a passive observer to a proactive antagonist in 'The Scarlet Letter', injecting themes of revenge and psychological torment into the narrative.
Step-by-step explanation:
The excerpt, "He (Chillingworth) became, thenceforth, not a spectator only, but a chief actor, in the poor minister's sinister world," eludes to the role of Roger Chillingworth in Nathaniel Hawthorne's novel, The Scarlet Letter. It signifies a transformation in his character from a mere observer to an active participant in Reverend Dimmesdale's life. This change reflects Chillingworth's decision to engage directly in influencing and manipulating the minister's existence as part of a personal vendetta.
Through Chillingworth's involvement, we observe a narrative shift highlighting themes of revenge, guilt, and the psychological torment that can ensue when one is consumed by vengeful desires. This transformation allows us to perceive Chillingworth as a symbol of malice, actively contributing to the downfall and further suffering of the tormented minister.