In "A Defence of Poetry,” Shelley suggests that emotions experienced in life are constantly changing. The following lines from "Mutability” can also be seen as a reflection of this idea:
We feel, conceive or reason, laugh or weep;
Embrace fond woe, or cast our cares away
This lines are saying that our emotions change, laugh reflects joy while weeping reflects sadness. Also, one can hold on to woes (sufferings) or one can let go of those. This lines are expressing different emotions one has and therefore reflects the idea that emotions are constantly changing throughout life.
