In the debate on the transnational transfer of planning ideas, many authors refer to a basic interpretive scheme of diffusion/dissemination that acknowledges an "origin" (contextualization) and a "destination" of the travel (recontextualization), with a thick "trajectory" in between (de-contextualization). This article questions such a scheme, arguing that planning ideas cannot be viewed as facts or truth statements, least of all fixed things that can be moved about. Rather, they are myths. Drawing upon Roland Barthes’ and Michel Foucault’s visions of modern mythology, the article envisages the origin narrative of a planning idea as a mythological narrative that planners may use to refresh their own knowledge and traditions each and every time an idea is put into play. An example taken from a planning event in the Middle East illustrates the practical implications of such an approach.