Main article: Metaphor and metonymy
Metaphor is distinct from metonymy, both constituting two fundamental modes of thought. Metaphor works by bringing together concepts from different conceptual domains, whereas metonymy uses one element from a given domain to refer to another closely related element. A metaphor creates new links between otherwise distinct conceptual domains, whereas a metonymy relies on pre-existent links within them.
In 1957, Jacques Lacan, inspired by an article by linguist Roman Jakobson, argued that the unconscious has the same structure of a language, and that condensation and displacement are equivalent to the poetic functions of metaphor and metonymy.