158 Life of Dr. J enner. 



Mankind vaccinate their children to escape the dangers of 

 small-pox : when, by the gradual lessening of the disease, such 

 dangers were removed from view, those who know any thing 

 of human nature, will at once perceive, that the preservative 

 practice would fall into neglect ; and so in fact it has ever 

 proved in countries where government does not enforce vac- 

 cination under penalties. So much for the common sense 

 view of the question. But we suspect the correctness of the 

 physiological principle on which the idea was upheld. It 

 assumes, in the first place, that small-pox in man arises inva- 

 riably from contagion, a position which we are strongly in- 

 clined to favour, but which is at least open to discussion. 

 The grease in horses, and the pock in cows, are universally 

 admitted (we believe even by Jenner himself) to be some- 

 times of spontaneous or sporadic origin. How otherwise 

 did it happen that, from 1780 to 1796, Jenner could meet 

 with no opportunities of prosecuting his inquiries into the 

 cow-pox ? Now, if we admit the identity of small-pox, 

 grease, and cow-pox, it is difficult to understand the extra'- 

 ordinary diversities in their mode of origin. If, on the other 

 hand, to establish the possibility of exterminating small-pox, 

 we adhere to its propagation by contagion alone, the identity 

 of the two diseases is certainly brought into doubt. 



But further, to show the correctness of this position of Dr. 

 Jenner, the state of small-pox in foreign countries is fre- 

 quently brought forward. It is confidently urged, that by 

 salutary regulations, and strong confidence in the public, the 

 desirable end proposed by Jenner has actually been accom- 

 plished, and that in some districts abroad small-pox is no 

 longer to be seen. We strongly suspect, however, that this 

 is what logicians call an argumentum ab ignoto. In Sweden, 

 one of the countries often referred to, they had a smart attack 

 of epidemic small-pox in 1824, affecting, in many cases, 

 those who had been vaccinated ; which, though it did not in 

 the least shake their faith in vaccination, yet proved very 

 efTectually the impossibility of exterminating the disease. 

 Within the last year or two, the Dutch government sent over 

 some young doctors to this country, to inquire concerning 

 vaccination, in consequence of meeting with difficulties of a 

 like kind. The medical men at Paris, who were long very 

 sceptical on the subject of small-pox after vaccination, under- 

 stand it now as well as we do here. We do not mention 

 these things out of any distrust of vaccination, but merely 

 that the superior good management of foreign powers, and 

 the greater good fortune of those who live under them (with 



