Symbolism, Imagery, Allegory
The Brothers Karamazov will sometimes break out a startling image to stand in for a concept. For example, Grushenka tells a story about an old woman whose guardian angel attempts to pull her out of hell with an onion (yes, all the angel could muster was an onion). When Grushenka mentions that her act of kindness is her "onion," the onion serves as shorthand for the idea that even one small act of goodness can redeem a soul. Another notable example is the "galloping troika" of the prosecutor's speech. Despite the narrator's ironic treatment of the prosecutor, the image of the galloping troika as a stand-in for a Russia careening out of control is powerfully evocative.