Between James Parkinson's 'shaking palsy' and the first report of the post-encephalitic manifestation — initially not recognizable as a complication of that incipient 'Spanish flu' epidemic — it took over a hundred years to arrive at a clear appreciation and differentiation of its most disabling feature: rigidity. This paper traces the development, step by hesitant or bold step, of the pertinent ideas and terms regarding muscle tone before and after Parkinson, their basis in neuropathological advances as they were made for (...) related syndromes of basal ganglia disorders, toward the eventual clinical correlation. Chief credits, after Sauvages, must go to Charcot for emphasizing the increase in muscle tone, and to Kinnier Wilson for establishing the extrapyramidal connection. (shrink)