How does John Donne's "A Valediction: Forbidding Mourning" reflect the metaphysical style?
Samuel Johnson coined the term "metaphysical" in the 18th century to describe a certain group of 17th century poets who Johnson rightly believed defied classical norms in poetry by writing sometimes difficult-to-understand verses that relied on jarring or unusual images or comparisons. Johnson disapproved: he sneered at the way these poets stretched their imaginations to find unusual images and connections. As Johnson put it, in the hands of the metaphysical poets:
The most heterogeneous [unlike] ideas are yoked by violence together.
In other words, the metaphysicals did what we might today call "mash-ups": they mashed (or yoked) together images and ideas that normally wouldn't be put side by side. A modern example would be the novel Pride and Prejudice and Zombies: who would pair Jane Austen with horror literature? (Of course, Pride and Prejudice is not a poem, but the same idea applies.) Some people love it and some people don't, but Zombies has us looking at Pride and Prejudice in new ways. So do the images and ideas in metaphysical poems.
To some extent, the metaphysicals were showing off, strutting their stuff and wanting to challenge their readers. Donne's "Valediction" is probably the most famous of these metaphysical poems. In this poem Donne tells his lover not to worry about death, because their souls are united. He doesn't use the conventional imagery or comparisons (metaphors or similes) of love poems: he doesn't liken his lover's eyes to stars or her cheeks and lips to rosebuds or her hair to gold wires or say that Cupid has shot arrows through his heart. He doesn't, as many of the "carpe diem" or "seize the day" love poems did, say the lovers have to seize every moment now because death might divide them. Donne rejects all these conventions and instead says he and his lover love on a higher plane: it is their souls that love and are united, and death is not to be worried about, because, like their love, it is not dependent on the body: the soul is eternal. Donne scoffs at
Dull sublunary [worldly] lovers' love(Whose soul is sense) [in other words, who are into each other's bodies]
[they] cannot admitAbsence, because it doth removeThose things [rosebud lips, etc] which elemented it.
In contrast, Donne says to his lover: "Our two souls ... are one."
Thus, if he dies, it won't be
A breach [a break], but an expansion,Like gold to airy thinness beat.
If they be two, they are two so
As stiff twin compasses are two;
Thy soul, the fix'd foot, makes no show
To move, but doth, if th' other do.
Like a compass, their souls will always move together, whether they are alive or dead. Nobody had ever described lovers this way before: so, either like Johnson you think this is a ridiculous image, mashing together two unlike things—love and a compass—or, like poets such as T.S. Eliot, you love the imaginative play of such a simile.