Jakobson pointed out that metaphor is an act of substitution of one term for another and thus corresponded to the paradigmatic axis, or the axis of selection. Metonymy is a relation of contiguity, in that one term refers to another because it is associated or adjacent to it, and therefore it corresponds to the syntagmatic axis, or the axis of combination. Lacan saw in Jakobson's structural model of metaphor and metonymy a direct correspondence with Freud's processes of dream work: condensation and displacement.
By mapping Jakobson's distinc-tion between metaphor and metonymy on to Freud's primary processes Lacan was finally able to demonstrate how the unconscious was struc-tured like a language. The unconscious, he argued, operates according to the rules of metaphor and metonymy.