She was one of those invalids who has to lie down a lot, and sometimes can't lift a bread knife, but can shift a mahogany wardrobe if the fancy is upon her to see it in a different place.
The passage describes a character who is often seen as fragile and incapacitated, having to spend considerable time in bed. Despite her apparent weakness, she possesses an unexpected strength, capable of moving heavy furniture when the motivation strikes her. This contrast highlights the complexity of her condition, illustrating how her physical limitations can be overcome by her will and determination at times.
This duality reflects the broader theme of personal resilience. It challenges the notion of disability by presenting a character who defies expectations, suggesting that individuals can possess strength in unexpected moments. The quote captures the essence of human experience, where limitations coexist with the capacity for surprising vigor and change.