Juxtaposition is the art of placing together a number of contrasting objects or ideas, usually two. Used effectively, it captures our imaginations immediately, making it one of the most valuable techniques any creator can employ to dramatize their message. And it’s at its most potent when these two objects are as diametrically opposed to each other as possible.
I remember learning that when painting if you want to make black seem even blacker then you juxtapose it with white. It’s as simple as that. So many artists have used this technique to add drama to their works. René Magritte’s Empire of Light, for example, shows an illuminated street at night, yet the blue sky above it belongs to a sunny day. That juxtaposition of night and day makes the picture.