in A Tale of Two Cities, what support can be given for the idea that revenge and justice conflict depending on what a person deems justifiable?

Perhaps the best example to support the question of individual interpretations of revenge and justice is in the relationship of Madame Therese Defarge and her husband, Ernest Defarge.

In Chapter XII of Book the Third, Sydney Carton has entered the wine shop in St. Antoine, and Madame Defarge recognizes him as a Evremonde (remember that Charles Darnay and he look alike). Her husband concurs that there is a resemblance, but he feels that in her...

Perhaps the best example to support the question of individual interpretations of revenge and justice is in the relationship of Madame Therese Defarge and her husband, Ernest Defarge.

In Chapter XII of Book the Third, Sydney Carton has entered the wine shop in St. Antoine, and Madame Defarge recognizes him as a Evremonde (remember that Charles Darnay and he look alike). Her husband concurs that there is a resemblance, but he feels that in her vengeance against the uncles Evremonde, the brothers who are responsible for the death of Therese Defarge's brother and sister, "one should stop somewhere." Brutally, she replies, "At extermination."

Monsieur Defarge does not agree that exterminating the entire family is just, pointing out that the wife of the one Marquis, the mother of Charles, sought to make amends and the good Dr. Manette, father of Lucie, the wife of Charles, has suffered terribly in the past and just recently. Mme. Defarge argues that Manette is not a true friend of the Republic. Furthermore, she informs her husband that she has had "this race," the family of Evremonde, in her register for a long time, doomed to destruction and extermination. She further explains her justification for avenging the death of her brother, her sister, and the unborn child, all of whom died at the hands of the Evremondes:

"...those dead are my dead, and that summons to answer for those things descends to me!"

Yet Defarge thinks she should not carry her revenge to the point of extermination of Darnay's family. Therese Defarge insists that she is justified, saying to her husband,

"Then tell Wind and Fire where to stop...but don't tell me."

M. Defarge appeals again to his wife to spare Darnay and his wife, who he feels are innocent, but she insists again, "Tell the Wind and the Fire where to stop; not me!"