Which theme is shared by the two poems?

Theme of impermanence: Both poems explore the theme of impermanence and the fleeting nature of life. In "To His Coy Mistress," the speaker urges his lover to seize the moment and enjoy their time together because life is short and uncertain. Similarly, in "When I Heard the Learn'd Astronomer," the speaker reflects on the vastness of the universe and the insignificance of human life, leading to a sense of the ephemeral nature of existence. Both poems convey the idea that time is precious and should not be wasted, as life is transient and opportunities may pass quickly.