Dickens begins the novel with antithesis, comparing London and England. In this case, he is drawing the reader to the concept of dualities from the start. He continues by describing many dualities. Here are some examples. The novel explores opposite concepts and opposite characters
A foil is a character who exists to present contrast. Consider the “honest tradesman” Jerry Cruncher, who is a resurrectionist because he is a grave robber. His despicable nature serves in direct contrast to the humble and responsible Jarvis Lorry, who is also a resurrectionist because he brings Dr. Manette back to life. Then of course there are the “twins” Sydney Carton and Charles Darnay, who are opposites in many ways. Carton is irresponsible, while Darnay is responsible. Carton is brilliant, while Darnay does some pretty dumb things.
Love and Hate
Thematically, love and hate are constantly contrasted in the novel. The novel is really a novel about love. Lucie and Charles Darnay, Lucie and her father, and Sydney Carton and Lucie are all relationships based on love. All are reciprocated except the last, of course. Yet we also have strong hate. Consider the Defarges, especially Madame Defarge. Dr. Manette even battles between love and hate within himself.
Sanity and Insanity
Dr. Manette is constantly teetering on the edge of insanity. His years in prison have left him broken, and he tries desperately to maintain his mind out of love for his daughter, but he often relapses when his emotions get the most of him. Similarly, Madame Defarge is not well, and Vengeance is even less stable.
Responsibility and Desire
There are many characters that want one thing, yet need another. Carton can barely avoid drinking himself to death, but he pulls himself out of it when he needs to. He has to do his job, because Stryver cannot do it. He also loves Lucie, but does not act on it because he knows she loves Charles. Charles, likewise, wants to remain in England and separate himself from his family, but in reality this is impossible. He is the Marquis St. Evremonde when his uncle dies, whether he likes it or not.
Life and Death
Throughout the novel, the concepts of life and death are juxtaposed—and not always literally. We have the revolution, which is the rebirth of a country, accomplished with bloody death. Darnay brings life to his family by marrying Lucie and having a daughter, but brings them to their doom because he cannot escape his past. Then there is the resurrection theme, as mentioned above.