Juxtaposition is usually used to create contrast, especially when two distinct images are juxtaposed in a hard way, meaning they are rhetorically slammed together on the page. Juxtaposition can create incredibly strong thematic points.

Perhaps the most famous example of juxtaposition in poetry is William Blake’s Songs of Innocence and Experience (1789), but an easy visual to help demonstrate the powerful effect of juxtaposition is Time Transfixed (1938)—a surrealist painting by Rene Magritte. This painting juxtaposes a train coming out of a fireplace like a tunnel. Above the train is a clock, transfixed forever in the still painting. The image has many strange qualities and tends to elicit different reactions in all viewers, but one way of reading it is as a juxtaposition of the many items the locomotive brought to the world, including set times, wealth, culture, and travel. The train’s physical elements are also illustrated by the fireplace’s physical properties: The train’s smokestack is like the pipe in a chimney and the smoke of the train is like the fire in the chimney.

Juxtaposition allows artists to craft striking images and to connect things that might not otherwise connect. And when done in a hard way, like how Magritte and Smith did it, the juxtaposition becomes jarring and unsettling, leading to tension and unease in readers and viewers.