'Eccentricity', by DH Tuke (1892).

An astronomical concept up to the eighteenth century, 'eccentricity' started to be used to refer to behaviours considered as odd, strange, rare, extravagant, etc. Once reified into a personality trait, it gained explanatory power. This not only increased its popularity but also facilitated its links with psychopathology and neuropsychology, and, via the shared concept of madness, with the notions of genius and creativity. This Classic Text describes the process whereby Alienism (Psychiatry) medicalized eccentricity. To this day, the latter remains firmly attached to 'psychoticism' and to some personality disorders.