John Donne's poetry has two major phases:
Early Donne: poetry is about physical love and the physical union of the male and female
Late Donne: poetry is about sin and guilt and the spiritual union between man and God
He uses metaphysical ("above," "beyond" the physical; spiritual; erotic; supernatural) conceits: elaborate and extended metaphors about the following subjects: alchemy, horticulture, astronomy, navigation, neo-Platonism, military, microcosm/macrocosm, law, and mathematics.
- "The Flea" uses the conceit of blood exchange to represent physical union (sex). The poem is a grand pick-up line: he's trying to convince her to go to bed. The conceit compares physical death to a kind of orgasm.
- "Forbidding Mourning" uses the conceit of a compass (geometrical instrument). The female is the fixed point and the male is the traveling pencil. He is away while she is at home, but if she waits for him, he will come "full circle" to form a symbol of love: the ring.