In book 2, chapter 7, of A Tale of Two Cities, the Marquis is in a bad mood, since he is out of favor in Parisian society. He has been driving his carriage through the streets at a high speed when he hits and kills a child. As the father of the child cries out in anguish, the Marquis arrogantly admonishes him for for failing to take proper care of his offspring. He then throws a gold coin out of the widow. When he hears another man, Defarge, the wine vendor, comforting the bereaved father, he says that Defarge is a philosopher and flings another gold coin at him.
The Marquis thinks he is being generous. He leans back in his carriage "with the air of a gentleman who had accidentally broke some common thing, and had paid for it," when the coin is thrown back into his carriage again. He is infuriated and tells the crowd that if he knew who had thrown the coin, he would happily drive his carriage over that man, crushing him beneath the wheels.
When the coin is tossed back at the Marquis, this shows the anger of the oppressed people and their refusal to accept his estimation of their value. A man cannot be compensated for the death of his child with a gold coin, and throwing the coin back at the Marquis with the same contempt he showed when he threw it out of the carriage is an assertion of this.