Goe, and catche a falling starre,
Get with child a mandrake roote,
Tell me, where all past yeares are,
Or who cleft the Divels foot,
Teach me to heare Mermaides singing,
Or to keep off envies stinging,
And finde
What winde
Serves to advance an honest minde.
Donne lists 4 more examples of impossible tasks. 
 
 No one knows what actually happens to the past, or how to go back there 
 The Devil’s foot is often portrayed as cleft as a goat’s paw, but who depicted it like that? Who says it is cleft? Again, no one knows 
 The song of a mermaid was known to be so amazing that it would lure men to dive in the water where they would be murdered. Donne wants to know how to be able to listen to it without giving into the temptation, but there is no way for that to happen. 
 Jealousy is a green-eyed monster, and anyone with someone worth loving is susceptible to suffering from envy. Again, it is impossible to not feel envy (at best you can hide it or control it). 
 
 It is interesting to note the juxtaposition of the real and the fantastic/fictional imagery in this stanza, which serves to blur the lines of reality, as well as make us think later on that a true woman is fictional and therefore doesn’t exist.
Song