At the end of Chapter 8 Elizabeth weeps, unhappy at the news of Justine’s death sentence. Victor uses a simile to describe her demeanor, comparing her unhappiness to a cloud:
But hers was the misery of innocence, which, like a cloud that passes over the fair moon, for a while hides, but cannot tarnish its brightness.
The novel portrays Elizabeth as gentle, kind, and extremely innocent. Elizabeth experiences great sadness in the wake of Justine’s death, an experience that threatens to ruin her radiant nature. However, Victor uses the phrase “misery of innocence” to suggest that this danger is mitigated in Elizabeth's case. He means that Elizabeth isn't jaded or cynical and that her unhappiness won't damage her "brightness" in the long run. Victor optimistically concludes that Elizabeth’s innocent nature will remain intact (a cloud "hides, but cannot tarnish" the bright moon). However, this proves not to be the case: Elizabeth is eventually murdered by the Monster.
Through Elizabeth's murder, the novel suggests that even the most genuine innocence is only temporary and that it is at the mercy of the darker aspects of human nature—even the darkness of other human beings can, tragically, snuff out the "brightness" of a pristine soul like Elizabeth's.