Throughout the 19th century, the discourse on idiocy was among the most substantial and celebrated fields of knowledge about human nature; yet it is mostly forgotten or ignored by scholars today. Once science could identify the truly retarded individual from within the confused concept of idiocy, it is thought, these subjects could finally be treated separately and more humanely. But looking back at the early discourse on idiocy reveals a rational knowledge of the subject built on a very different intelligibility from our own. Indeed, until modern times, idiocy was actually considered a form of madness, and it was only through the emergence of a new intelligibility of the body--based on the idea of development--that the concept of retardation could emerge. Rather than through medical or humanistic advance, it was first through the emergence of the normalizing technologies of the hospitals and schools that society would find new reasons and means for dealing with these "recalcitrant" figures who were unwilling or unable to conform to the requirements and goals of the institutional disciplines. A new intelligibility of the idiot based on new disciplinary technologies would provide the basis not only for the mentally retarded subject, but eventually for all of the behavioral disorders of childhood. This article will be of interest to scholars and educators interested in the history of the modern developmental subject, pedagogy, and the appearance of the norm in constructing knowledge of the subject and the ordering of behaviors.