Metaphor and metonymy

Metaphor (drawing a similarity between two things) and metonymy (drawing a contiguity between two things), are two fundamental opposite poles along which a discourse with human language is developed. It has been argued that the two poles of similarity and contiguity are fundamental ones along which the human brain is structured; in the study of human language the two poles have been called metaphor and metonymy, while in the study of the unconscious they have been called condensation and displacement.

The couple metaphor-metonymy had a prominent role in the renewal of the field of rhetoric in the 1960s.

In the unconscious: condensation and displacement
According to Freud's work (1900), condensation and displacement (from German Verdichtung and Verschiebung) are two closely linked concepts. In the unconscious, through the dynamic movement of cathexis (charge of libido, mental or emotional energy), it is possible that an idea (image, memory, or thought) passes on its whole charge to another idea; Freud called this process "displacement." It is also possible that a single idea takes the whole charge of more than one other ideas; Freud called this process "condensation." In other words, a condensation is when more than one displacement occurs towards the same idea.

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.