The opening lines of A Tale of Two Cities by Charles Dickens may be some of the famous lines in English-language literature. The rhythm and parallel content and structure of the lines evokes many questions about the story to come and sets the stage for a tale of conflict and opposing perspectives.

The book begins:

It was the best of times, it was the worst of times, it was the age of wisdom, it was the age of foolishness, it was the epoch of belief, it was the epoch of incredulity, it was the season of Light, it was the season of Darkness, it was the spring of hope, it was the winter of despair, we had everything before us, we had nothing before us, we were all going direct to Heaven, we were all going direct the other way—in short, 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.

Some of these pairs of descriptors seem to be impossible contrasts. How can it be both "the best of times" and "the worst of times"? As Book the First unfolds, it becomes clear that while for some it was indeed a fine time to be living in France, for others life was brutal and heartbreaking.

In chapter 4, "The Preparation," Mr. Lorry, the banker from Tellson's, reveals to Miss Manette that her father is not dead, as she had been told all her life, but that he was in fact missing and has been discovered alive. Mr. Lorry remembers bringing Miss Manette to England as a young child after her mother also died and has not seen her since. She has grown up into a pretty young woman, living in England.

This scene is "the best of times" because Miss Manette learns that, rather than being an orphan, she has the opportunity to meet her long-lost father. Mr. Lorry is able to give her this wonderful news and also be reunited with the child he knew so long ago under sadder circumstances.

It is also "the worst of times" because her father has been missing for most of her life and has been discovered in poor condition, described by Mr. Lorry as "almost a wreck." Mr. Lorry tells her they do not know, and cannot ask now, whether her father has been a prisoner or if there is another reason they weren't able to find him. He has been living under another name, but it is not clear why, or if he remembers his original name. Having heard "the best and the worst" of the news Mr. Lorry has to share, Miss Manette becomes "utterly insensible" from the shock and needs to be revived with smelling salts and other treatments. This tension between opposites—relief and shock, happiness and sorrow—is present throughout A Tale of Two Cities.

You are right in identifying parallelism as a major stylistic tool that is employed in this incredible novel. The main conflicts of the novel are referred to in the famous opening chapter, that draws our attentions to the strange dichotomy of the times:

It was the best of times, it was the worst of times, it was the age of wisdom, it was the age of foolishness, it was the epoch of belief, it was the epoch of incredulity, it was the season of Light, it was the season of Darkness, it was the spring of hope, it was the winter of despair...

You might want to think how such opposition is created by the way that characters are matched against each other and also events repeat themselves. For example, Charles Darnay and Syndey Carter are doubles of each other, with Charles Darnay representing the goodness that Syndey Carter seems unable to find within himself until the final pages of the novel. Equally, both Dr. Manette and Madame Defarge are victims of the French aristocracy. Charles Darnay suffers two trials in the pages of the novel, one where he is charged as a traitor of Britain, the other when he is charged as a traitor of France. Lucie is opposed to Madame Defarge, who, towards the end of the novel, increasingly psychologically dominates her. And lastly, of course, lest we forget the title, this is a tale of two cities and how both effect each other. Doubles or matches abound in the novel, and parallelism is established as a manner of introducing conflict and highlighting themes.