In "A Defence of Poetry," Shelley suggests that emotions experienced in life are constantly changing. Which lines from "Mutability" can also be seen as a reflection of this idea? Streaking the darkness radiantly!—yet soon Night closes round, and they are lost for ever We rest.—A dream has power to poison sleep; We rise.—One wandering thought pollutes the day We feel, conceive or reason, laugh or weep; Embrace fond woe, or cast our cares away Man’s yesterday may ne’er be like his morrow; Nought may endure but Mutability.