FALLACIES OF SIMPLE INSPECTION. 333 



motions of bodies originate. We need scarcely refer to con- 

 tagion, fermentation, and the like; or to the production of 

 effects by the growth or expansion of a germ or rudiment 

 resembling on a smaller scale the completed phenomenon, as 

 in the growth of a plant or animal from an embryo, that 

 embryo itself deriving its origin from another plant or animal 

 of the same kind. Again, the thoughts, or reminiscences, 

 which are effects of our past sensations, resemble those 

 sensations ; feelings produce similar feelings by way of sym- 

 pathy ; acts produce similar acts by involuntary or voluntary 

 imitation. With so many appearances in its favour, no wonder 

 if a presumption naturally grew up, that causes must neces- 

 sarily resemble their effects, and that like could only be 

 produced by like. 



This principle of fallacy has usually presided over the 

 fantastical attempts to influence the course of nature by 

 conjectural means, the choice of which was not directed by 

 previous observation and experiment. The guess almost 

 always fixed upon some means which possessed features of 

 real or apparent resemblance to the end in view. If a charm 

 was wanted, as by Ovid's Medea, to prolong life, all long-lived 

 animals, or what were esteemed such, were collected and brewed 

 into a broth : 



. . . . nee defuit illic 

 Squamea Cinyphii tenuis inembrana chelydri 

 Vivacisque jecur cervi : quibus insuper addit 

 Ora caputque novem cornicis saecula passse. 



A similar notion was embodied in the celebrated medical 

 theory called the " Doctrine of Signatures," " which is no 

 less," says Dr. Paris,* " than a belief that every natural 

 substance which possesses any medicinal virtue indicates by 

 an obvious and well-marked external character the disease for 

 which it is a remedy, or the object for which it should be 

 employed." This outward character was generally some 

 feature of resemblance, real or fantastical, either to the effect 



* Pharmacologia, pp. 43-5. 



