Light and dark imagery is used throughout the novel. From the very first chapters we are introduced to a shadowy, dark, scarry world - the mist and darkness enshrouding the mailcoach is a perfect example. The appearance of Lucie also perpetuates this imagery, as the darkness in the room is described as being so strong that the light from the candle offers little respite.
Shadows and darkness continue to fall across the rest of the novel. In particular, Madame Defarge casts a shadow on Lucie and her hopes of freeing her husband. For example, as Lucie stands in the fresh, white snow, Madame Defarge passes like a "shadow over the white road". Likewise the letter written by Dr. Manette casts a shadow over the whole family. It is highly significant that the chapter in which the letter is read out is entitled "The Substance of the Shadow".
Against this darkness light is represented through the character of Lucie, and in particular "The Golden Thread" of her hair.
There are a number of dark instances being used starting in the first chapter where the author speaks of all the criminals reigning terror on the people to such an extent that it all seems normal. He ends this point by talking of the man who is ever so busy hanging criminals one after another, sometimes in groups, every single day: “hanging a housebreaker on Saturday who had been taken on Tuesday; now, burning people in the hand at Newgate by the dozen.” The steaming mist and darkness that looked like an “evil spirit” also goes to show some level of dark imagery. In the third chapter light is seen with the rising of the sun which was bright, placid and beautiful “though the earth was cold and wet, the sky was clear, and the sun rose bright, placid, and beautiful.”