Idea
spirits guarding treasure
Drayton's using a specific folklore belief: treasure spirits were bound by magic to guard buried wealth. The spirit can't leave, but also won't give it up—it's trapped in service.
the paradox of pursuit
Notice the reversal: the closer you get to grabbing the treasure, the further it retreats. This is the poem's central mechanism—desire creates distance, not closeness.
You as the spirit
The volta shifts the metaphor: you're not the treasure-seeker, you're the trapped spirit. Your beauty is the wealth being guarded, and you're the one holding it back from others.
coldness, not cruelty
"Coldness of your blood" suggests emotional detachment, not malice. The problem isn't that you're mean—it's that you're withholding from indifference, which Drayton frames as worse.