In Chapter III of Book the First of A Tale of Two Cities, Charles Dickens intrudes into the narrative with the reflection,
...every human creature is constituted to be that profound secret and mystery to every other. A solemn consideration, when I enter a great city by night, that every one of those darkly clustered houses encloses its own secret; that every room in every one of them encloses its own secret; that every beating heart in the hundreds of thousands of breasts there, is, in some of its imaginings, a secret to the heart nearest it! Something of the awfulness, even of Death itself, is referable to this.
Now again, in Chapter VI of Book the Second, a similar phrase finds itself as the title of the chapter. While on the one hand it is Miss Pross's hyperbole for the people who come to call on her "Ladybird" and signifies Miss Pross's frustration about the Manette's privacy being invaded and the subjection of her beloved Lucie to gentlemen callers whom Miss Pross perceives only as an annoyance, it also foreshadows the "hundreds of thousands" whose "secret in their hearts" will soon be revealed as the French Revolution breaks out.
As she stands with Charles Darnay, Lucie and he hear a "great hurry in the streets," of people fleeing a storm, there are "echoes of footsteps coming and going, yet not a footstep was there." Lucie's premonition that these are the echoes of footsteps that will come into their lives and Sydney Carton's remark, "There is a great crowd coming one day into our lives," prepare the reader for the events of Book the Third. Even Dickens, as narrator, contributes to the melodrama of the moment, suggesting the mob mentality to come:
Perhaps. Perhaps, see the great crowd of peole with its rush and roar, bearing down upon them, too.