In Nathan's creative writing class, he learned some writers make surprising, interesting, or amusing contradictions in their work. Which literary device did Nathan learn about?

The literary device that Nathan learned about is called a paradox. Paradox usually matches things that you wouldn't normally match because one negates the other. For example: I know one thing - that I know nothing. This sentence is self-contradictory, and thus it is paradoxical. Usually there is a funny or silly effect to this literary device.