The nineteenth century concept of ‘disorder of motility’ is one of the most difficult to grasp from the perspective of today. This tells much about the role of ideology and metaphor in descriptive psychopathology. For what might have in common clinical states as diverse as stupor, akinesia, catalepsy, psychomotor retardation, agitation, impulsions, bradyphrenia, parkinsonism, dyskinesias akathisia, grimacing, mannerisms, posturing, stereotypies, soft neurological signs, tremors and tics except, perhaps, the fact that they all refer in a general way to human movement? Confronted with such a list, the neurologist of today might respond as he would to a medieval bestiary, i.e. with amused disbelief. Of the old disorders of motility he will say that they are either involuntary movements of basal ganglia origin or psychogenic disorders, i.e. Voluntary' movements pretending to be otherwise.

Unfortunately, things are not as simple as this. For what is the status of catatonia or depressive stupor? Are they basal ganglia phenomena? Are they just ‘psychogenic’ states under the patient's control? Is it that he cannot move or that he does not want to? Should the complaint that he cannot move ever be taken seriously? On the other hand, is the ‘cannot’ of stupor analogous to the ‘cannot’ of hysterical paralysis? Where are the empirical answers to these questions? Should we accept Ajuriaguerra's ‘psychomotor syndromes’, or Hunter's ‘brain disease’ view, or Marsden et al.'s ‘areas of common interest’, or the ‘conflict of paradigms’ view? One approach to these complex issues is historical analysis, i.e. the going back in time to a period when dichotomies such as voluntary-involuntary, cortical-sub-cortical, and organic-psychogenic had not yet been invented.