534 FALLACIES. 



Conformably to what we have before remarked to be of frequent occur- 

 rence, this fallacy might without much impropriety have been placed in a 

 different class, among Fallacies of Generalization ; for experience does af- 

 ford a certain degree of countenance to the assumption. The cause does, 

 in very many cases, resemble its effect; like produces like. Many phe- 

 nomena have a direct tendency to perpetuate their own existence, or to 

 give rise to other phenomena similar to themselves. Not to mention 

 forms actually moulded on one another, as impressions on wax and the 

 like, in which the closest resemblance between the effect and its cause is 

 the very law of the phenomenon ; all motion tends to continue itself, with 

 its own velocity, and in its own original direction ; and the motion of one 

 body tends to set others in motion, which is indeed the most common of 

 the modes in which the motions of bodies originate. We need scarcely 

 refer to contagion, fermentation, and the like ; or to the production of ef- 

 fects 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 ; feel- 

 ings produce similar feelings by way of sympathy; acts produce similar 

 acts by involuntary or voluntary imitation. With so many appearances in 

 its favor, no wonder if a presumption naturally grew up, that causes must 

 necessarily resemble their effects, and that like could only be produced by 

 like. 



This principle of fallacy has usually presided over the fantastical at- 

 tempts to influence the course of nature by conjectural means, the choice 

 of Avhich 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 w'anted, 

 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 membrana cheb'dii 

 Vivacisque jecur cervi : quibus insnper addit 

 Ora caputque novem cornicis sajcula passoe. 



A similar notion was embodied in the celebrated medical tlieory 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 featiu'e of resemblance, real or 

 fantastical, either to the effect it was supposed to produce, or to the phe- 

 nomenon over which its power was thought to be exercised. "Thus the 

 lungs of a fox must be a specific for asthma, because that animal is re- 

 markable for its strong powers of respiration. Turmeric has a brilliant 

 yellow color, which indicates that it has the power of curing the jaundice; 

 for the same reason, poppies must relieve diseases of the head ; Agaricus 

 those of the bladder ; Cassia fistula the affections of the intestines, and 

 Aristolochia the disorders of the uterus : the polished surface and stony 

 hardness which so eminently characterize the seeds of the Lithospermum 

 officinale (common gromwell) were deemed a certain indication of their 



* Pharmacologia, pp. 43-45, 



