1895-96-] Popular Delusions in Natural History. 169 



meaning witnesses with that tendency to scepticism which grows 

 with scientific education and scientific mode of thought. 



A popular delusion is a helief, widely spread among people 

 of a certain stage of scientific education, in a supposed fact 

 which, however the belief may have arisen, is proved by 

 accurate information to be not a fact. Other beliefs, again, 

 may be only reputed popular delusions, because they are so 

 inconsistent with actual knowledge that the trained scientific 

 mind cannot possibly accept them. As an example of the 

 first, we may instance the belief, not yet extinct even among 

 educated people, that as a memento of the peculiar method 

 in which Eve was called into existence, a man has one rib 

 less than a woman. Here the simple process of counting the 

 ribs in a male skeleton settles the matter at once in favour 

 of the sceptical scientist. As an example of the second, we 

 may take the repeated occurrence of live frogs and toads in 

 the centre of blocks of stone, — a belief which we shall see 

 further on is so absolutely and ludicrously opposed to all that 

 we know both of the physiology of the Amphibia or of the 

 geological formation of the earth's crust, that we are compelled 

 simply to say, " We don't believe it." 



In dealing with alleged phenomena which are at the same 

 time avowedly natural, a popular delusion essentially differs 

 from a superstition, into which the element of the supernatural, 

 or at least of the " uncanny," always enters. As being on the 

 border line, I may, however, instance the idea prevalent in 

 some parts of the country that a shrew-mouse dies if it 

 attempts to cross a road. But, of course, beliefs in fairies, 

 witches, ghosts, wraiths, unlucky things, &c, &c, however 

 widely spread, are absolutely removed from the category of 

 delusions with which we are this evening to deal. 



Also, in being not only widely spread, but more or less self- 

 contained, and chiefly the result of ignorance or of imperfect 

 and untrained powers of observation, a popular delusion differs 

 completely from what is called a " fad." A fad is an erroneous 

 view or theory, typically the property of a few, and these not 

 always of the most uneducated, which owes its origin to an 

 undue bias of the mind on some particular subject, by which 

 the efficacy of the reasoning powers as to matters connected 

 therewith becomes seriously impaired, while the most obvious 



