In Charles Dickens's A Tale of Two Cities, Book the Second, Chapter 15, the "fools" of whom Ernest DeFarge speaks are the French aristocrats, particularly King Louis XVI and his queen, Marie Antoinette who travel pass the DeFarges and the mender of roads. They are fools because they do not perceive the unrest and rebellion that is burgeoning in the peasantry who have been exploited for so long.
Recently, the father of the boy who was run over by the carriage of the Marquis de Evremonde, clung to the bottom of this carriage in order to kill the callously cold Marquis. But, he was captured and his arms bound, and hanged in spite of Ernest DeFarge's having brought a signed peition that begged the Marquis to save his life. So, Madame DeFarge "registers" the entire family of the Evremondes for death after this cruel act.
Later, when the King and Queen pass along roads near them, the DeFarges taken the mender of roads to see them. As they pass, he cheers as he sees the royalty; DeFarge congratulates him saying, "You make these fools believe it [the present state of oppression by the aristocrats] will last forever."
It is significant that the ironically named "mender of roads" is witness to the passing of the royalty. This metaphoric character, introduced earlier in the novel, along with the Woodman, Fate, and, the Farmer, Death, will effect the blood spilling presaged in Chapter 5 of Book the First, "the Wine Shop."