ABSTRACT
There is no doubt that classical antiquity and the Middle Ages regarded monstrosity as an effect of the monstrous. The Middle Ages retain the identification of the monstrous with the felonious, but enrich it with a reference to the diabolic. The monster is both the effect of an infringement of the rule of the sexual segregation of species and the mark of a desire to pervert the table of creatures. The scientific explanation of monstrosity and the correlative reduction in the importance of the monstrous really develops in the nineteenth century. Teratology is born at the point where comparative anatomy meets an embryology reformed by the adoption of the theory of epigenesis. Monstrosity is the fixation of the development of one organ at a stage the others have surpassed. It is the survival of a transitory embryonic form. For an organism of a given species, today’s monstrosity is the day before yesterday’s normal state.
