This article considers the meaning of the term “function” in functional neurological disorders. It does so through the dual lens of neuropsychoanalysis, focusing mainly on the development of the concept in Sigmund Freud's early work and Karl Friston's recent work. Specifically, the article addresses two questions: (1) What sort of physical process turns an anatomical structure into an idea? (2) What sort of physical process renders ideas conscious? The author concludes that neurologists and psychoanalysts working on the problem of functional neurological disorders are now speaking a common language: that of predictive processing and its organizing Free Energy Principle.