What medicine of the classical age admitted unproblematically, the foundation upon which it progresses without asking itself any questions, was a different form of simplicity, more complex for us, as since the nineteenth century we are used to thinking the problems of psychiatry in terms of an opposition between body and mind (an opposition that is merely attenuated and eluded by notions like 'organo or 'psychogenesis'), it was the simplicity that Tissot presented as a defence against the abstract chimera of the philosophes, the beautiful, discernible unity of body and soul, which precedes all the dissociations unknown to medicine: