How does george herbert use the story of echo in his poem "heaven"?

herbert uses narcissus' rejection of echo to illustrate a holy man's rejection of mortal love for the eternal love of god.
herbert uses the idea of unrequited love and the despair it causes as the theme of his poem.
herbert uses only the idea of a nymph in love with a young man in his poem.
herbert uses the idea of one who can only repeat part of an answer as a device in his poem.