An Essay on the Shaking Palsy

An Essay on the Shaking Palsy is a medical book on Parkinson's disease written by James Parkinson, an English surgeon, apothecary, geologist, palaeontologist, and political activist. 

Author's Preface:

The advantages which have been derived from the caution with which hypothetical statements are admitted, are in no instance more obvious than in those sciences which more particularly belong to the healing art. It therefore is necessary, that some conciliatory explanation should be offered for the present publication: in which, it is acknowledged, that mere conjecture takes the place of experiment; and, that analogy is the substitute for anatomical examination, the only sure foundation for pathological knowledge.