When Lady Dedlock learns from Mr. Guppy that Esther's real last name is "Hawdon," she undergoes a ghoulish and visible transformation that paradoxically makes her seem both alive and dead. Dickens uses a simile to describe this state of extreme shock and torpor. After receiving this news, Lady Dedlock appears to Guppy to be
for the moment, dead. He sees her consciousness return, sees a tremor pass across her frame like a ripple over water, sees her lips shake, sees her compose them by a great effort, sees her force herself back to the knowledge of his presence, and of what he has said [...] her dead condition seem to have passed away like the features of those long-preserved dead bodies sometimes opened up in tombs, which, struck by the air like lightning, vanish in a breath.
The visual imagery of this horrifying realization is full of delicate, shivering diction. The simile of the tremor passing over Lady Dedlock like a "ripple over water" makes the reader feel the shudder that engulfs her after hearing this portentous news. To Guppy she seems—in this moment—"dead," but the death isn't permanent. Instead, the "death" washes over her like a "ripple of water" before she can compose herself. Like a ripple in a pond, it dissipates quickly, but not before it gives the reader a powerful impression of the (usually cold and stoic) Lady Dedlock's fragility. She teeters on the edge of a breakdown in this passage, seeming to pass out of the world before her consciousness can "return."
Lady Dedlock is usually totally composed, but in this scene Dickens uses visual language to imply that her character has become incredibly brittle, like a corpse decayed to powder and paper in a tomb. To Guppy, the action of cracking her emotional shell seems like it might literally disintegrate her body. When she hears the news, she reminds Guppy of a corpse "struck by the air like lightning," suddenly so fragile she might crumble away. Of course, Lady Dedlock isn't dead or rotted to powder, because she doesn't "vanish in a breath," but this scene underscores just how startling Guppy's revelation is.