Why is the poet in search of the spring? Where does he hope to find it?

The poet in the poem "Song: Go and Catch a Falling Star" is in search of the mythical spring that has the power to heal all illnesses, including the sickness of love. He hopes to find it at the end of the world, beyond the Ganges river, or in the lap of the fairy queen. However, the search for this spring is also a metaphor for the search for an ideal and perfect woman who is faithful, constant, and true, a search that the speaker believes is just as futile as the search for the mythical spring.