Much of the action of A Tale of Two Cities takes place in Paris during the French Revolution, which began in 1789. In A Tale of Two Cities, Dickens shows how the tyranny of the French aristocracy—high taxes, unjust laws, and a complete disregard for the well-being of the poor—fed a rage among the commoners that eventually erupted in revolution. Dickens depicts this process most clearly through his portrayal of the decadent Marquis St. Evrémonde and the Marquis' cruel treatment of the commoners who live in the region under his control.
However, while the French commoners' reasons for revolting were entirely understandable, and the French Revolution was widely praised for its stated ideals of "Liberty, Equality, and Fraternity," Dickens takes a more pessimistic view. By showing how the revolutionaries use oppression and violence to further their own selfish and bloodthirsty ends, in A Tale of Two Cities Dickens suggests that whoever is in power, nobles or commoners, will fall prey to the temptation to exercise their full power. In other words, Dickens shows that while tyranny will inevitably lead to revolution, revolution will lead just as inevitably to tyranny. The only way to break this cycle is through the application of justice and mercy.
Everybody in A Tale of Two Cities seems to have secrets: Dr. Manette's forgotten history detailed in his secret letter; Charles's secret past as an Evrémonde; Mr. Lorry's tight-lipped attitude about the "business" of Tellson's Bank; Jerry Cruncher's secret profession; and Monsieur and Madame Defarge's underground activities in organizing the Revolution. In part, all this secrecy results from political instability. In the clash between the French aristocracy and revolutionaries, both sides employ spies to find out their enemies' secrets and deal out harsh punishments to anyone suspected of being an enemy. In such an atmosphere, everyone suspects everyone else, and everyone feels that they must keep secrets in order to survive.
Through the secrets kept by different characters, A Tale of Two Cities also explores a more general question about the human condition: what can we really know about other people, including those we're closest to? Even Lucie cannot fathom the depths of Dr. Manette's tortured mind, while Sydney Carton remains a mystery to everybody. Ultimately, through Lucie's example, the novel shows that, in fact, you can't ever know everything about other people. Instead, it suggests that love and faith are the only things that can bridge the gap between two individuals.
Madame Defarge with her knitting and Lucie Manette weaving her "golden thread" both resemble the Fates, goddesses from Greek mythology who literally controlled the "threads" of human lives. As the presence of these two Fate figures suggests, A Tale of Two Cities is deeply concerned with human destiny. In particular, the novel explores how the fates of individuals are shaped by their personal histories and the broader forces of political history. For instance, both Charles and Dr. Manette try to shape and change history. Charles seeks to escape from his family's cruel aristocratic history and make his own way in London, but is inevitably drawn "like a magnet" back to France where he must face his family's past. Later in the novel, Dr. Manette seeks to use his influence within the Revolution to try to save Charles's life from the revolutionaries, but Dr. Manette's own forgotten past resurfaces in the form of an old letter that dooms Charles. Through these failures of characters to change the flow of history or to escape their own pasts, A Tale of Two Cities suggests that the force of history can be broken not by earthly appeals to justice or political influence, but only through Christian self-sacrifice, such as Carton's self-sacrifice that saves Charles at the end of the novel.
A Tale of Two Cities is full of examples of sacrifice, on both a personal and national level. Dr. Manette sacrifices his freedom in order to preserve his integrity. Charles sacrifices his family wealth and heritage in order to live a life free of guilt for his family's awful behavior. The French people are willing to sacrifice their own lives to free themselves from tyranny. In each case, Dickens suggests that, while painful in the short term, sacrifice leads to future strength and happiness. Dr. Manette is reunited with his daughter and gains a position of power in the French Revolution because of his earlier incarceration in the Bastille. Charles wins the love of Lucie. And France, Dickens suggests at the end of the novel, will emerge from its terrible and bloody revolution to a future of peace and prosperity.
Yet none of these sacrifices can match the most important sacrifice in the novel—Sydney Carton's decision to sacrifice his life in order to save the lives of Lucie, Charles, and their family. The other characters' actions fit into the secular definition of "sacrifice," in which a person gives something up for noble reasons. Carton's sacrifice fits the Christian definition of the word. In Christianity, God sacrifices his son Jesus in order to redeem mankind from sin. Carton's sacrifice breaks the grip of fate and history that holds Charles, Lucie, Dr. Manette, and even, as the novel suggests, the revolutionaries.
Closely connected to the theme of sacrifice is the promise of resurrection. Christianity teaches that Christ was resurrected into eternal life for making the ultimate sacrifice (his death) for mankind. Near the end of A Tale of Two Cities, Carton remembers a Christian prayer: "I am the resurrection and the life." As he goes to the guillotine to sacrifice himself, Carton has a vision of his own resurrection, both in heaven and on earth through Lucie and Charles's child, named Sydney Carton, whose life fulfills the original Carton's lost potential. Yet Carton's is not the only resurrection in the novel. After having been imprisoned for years, Dr. Manette is "recalled to life" by Lucie's love. Jerry Cruncher, meanwhile, works as a "resurrection man" stealing body parts from buried corpses, but by the end of the novel he gives it up in favor of praying for a holier resurrection of his own.
In the novel, the Bastille symbolizes the nobility's abuse of power, exemplified by the unjust imprisonment of Dr. Manette by Marquis St. Evrémonde. Yet the Bastille is not the only prison in A Tale of Two Cities. The revolutionaries also unjustly imprison Charles in La Force prison. Through this parallel, Dickens suggests that the French revolutionaries come to abuse their power just as much as the nobility did.
The theme of imprisonment also links to the theme of history and fate. For instance, when Charles is drawn back to Paris because of his own past actions, each checkpoint he passes seems to him like a prison door shutting behind him.