Dickens wrote A Tale of Two Cities as an exploration of love and sacrifice, and as a warning that the poor should not be ignored.
To understand why Charles Dickens wrote A Tale of Two Cities, we need to understand both his personal beliefs and the historical context. Dickens believed that no individual or group had a right to victimize another, and that the poor are everyone’s responsibility. At the time he wrote the story, he was concerned that the uprisings in the American colonies and France was a danger for England.
[The] period was so far like the present period, that some of its noisiest authorities insisted on its being received, for good or for evil, in the superlative degree of comparison only. (Book 1, Ch 1, p. 4)
Historically, England was suffering under the weight of industrialization. The Poor Law and church charities were ineffective in keeping people fed and clothed and with a roof over their heads. Dickens wanted to use the Russian Revolution as a cautionary tale because he saw the same conditions in England that led to revolution in France.
Dickens also wrote the book because he wanted to explore the redemptive power of love. Dickens was definitively a romantic. His view of love was not very pragmatic. Sydney Carton demonstrates his love by dying so that the woman he loves can love the man she loves.
“It is a far, far better thing that I do than I have ever done; it is a far, far better rest that I go to than I have ever known.” (Book 3, Chapter 15, p. 241)
Dickens appreciates Carton’s sacrifice and the purity of Lucie’s love. The story is beautiful, but not very practical. Love can be about sacrifice, but not the ultimate sacrifice. Love redeems both Carton and Darnay, and Dickens desperately wanted love to be redemptive, because his personal love life was difficult.