A grey cat, dragging its belly, crept across the lawn, and a black one, its shadow, trailed after. The sight of them, so intent and so quick, gave Bertha a curious shiver.
First time when cats appear they bring a mysterious and curios touch to the story. When you read about the two cats they seem to mean something, but you cannot figure it out
And then she was gone, with Eddie following, like the black cat following the grey cat.
The second time when the cats appear they bring a fatal feeling. Like Berthas feelings already had been a warning of coming danger. The cats make the reader think about the deeper meaning of the text.
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