Read the passage from "Mutability.” We are as clouds that veil the midnight moon;
How restlessly they speed, and gleam, and quiver,
Streaking the darkness radiantly!—yet soon
Night closes round, and they are lost for ever:

By contrasting "darkness” with "radiantly,” Shelley

emphasizes that although life is fleeting, it is exciting.
compares the spark of creativity to the enduring night sky.
introduces the idea that people are destined to live life in darkness.
explains that people are permanent, bright fixtures like the heavens.