“The Nymph’s Reply to the Shepherd” is Sir Walter Raleigh’s response to a poem written by Christopher Marlowe, “The Passionate Shepherd to His Love.” In the Marlowe poem, the shepard is promising the world and all it's earthly pleasures to his love.
The nymph responds in Raleigh's poem that while the shepherd’s gifts might be desirable, but they too are transient: they “soon break, soon wither” and are “soon forgotten." and rejects the shepard.
In the end, the nymph acknowledges that she could accept the shepherd’s offer only if things would never change. Like the shepherd, she wishes these things were possible, but like the poet Raleigh she is a skeptic, and only has faith in reason to discount the “folly” of “fancy’s spring.”