this article uses paedophile, an object built by legal medical knowledge, as a pretext to present one of the articulation points of two knowledge: pedagogical and physician, parts of the truthful device on homosexuality presented in Antioky at the end of the 19th century. This device sets out some of its bases and models in the urban planning manuals, which are subsequently assessed by legal medical knowledge when the restraint reaches it, once it becomes dissident of a ‘duty to be’.