How does Dickens symbolically show the effect of Madame Defarge on Lucie in A Tale of Two Cities, Book III Chapter Three?

One of the many recurring symbols in this excellent and
poignant Dickensian classics is that of the shadow, which is in fact the title given to
this chapter which charts the first meeting between Madame Defarge and Lucie Manette.
Interestingly, when Lucie is first introduced to Madame Defarge, she greets her in a way
that shows her simplicity, innocence and love, yet Madame Defarge remains unmoved by
such a display of emotion:

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[Lucie] turned from Defarge to his wife, and
kissed one of the hands that knitted. It was a passionate, loving, thankful, womanly
action, but the hand made no response--dropped cold and heavy, and took to its knitting
again.

So unresponsive is
Madame Defarge to this gesture that Lucie "looks terrified" at Madame Defarge, who only
gives her a "cold, impassive stare." However, it is when Madame Defarge realises that
the baby is Evremonde's child that we see the true symbolic effect of the shadow and how
it operates through the character of Madame Defarge to reach out and intimidate others.
Note the description Dickens gives us after Madame Defarge has established the identity
of the baby:

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The shadow attendant on Madame Defarge and her
party seemed to fall so threatening and dark on teh child, that her mother instinctively
kneeled on the ground beside her, and held her to her breast. The shadow attendant on
Madame Defarge and her party seemed then to fall, threatening and dark, on both the
mother and the child.

Notice
how the symbolism of the shadow seems to function in a way that foreshadows the harm
that Madame Defarge will do to the family of Charles Darnay, and her attempt to take
both the life of Lucie and their daughter.