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hardly aware of the experience that is needed to discriminate 

 between what is real and what is um-eal, even when one's own self 

 is the observer. It not unfrequently happens in Natural History 

 that the most absurd mistakes are made by those not habituated 

 to close and accurate obsei^vation, as in one instance by a gentleman, 

 whom I heard asserting that humming birds were found in this 

 country, from his having seen the humming-bird hawk moth 

 hovering over the flowers in a garden and mistaken it for a real 

 bird. Many other cases might be mentioned in which the pro- 

 ductions of nature so closely resemble each other in a general way 

 that an unpractised eye can hardly distinguish between them. It 

 is necessary sometimes to look again and again before we can be 

 sure of what we really see. 



And if caution is required in judging of our own observations, how 

 much more is it needed in judging of those of others. How slow 

 should we be to receive as facts, what rest entirely upon state- 

 ments which we cannot verify, and which perhaps amount to nothing 

 more than mere popular beliefs handed down from father to son. 

 Gentlemen, I would appeal to you, as having, I should imagine, 

 often found the necessity for exercising this caution in your various 

 excursions. You visit strange places ; you are struck with certain 

 matters of interest that fall under your notice ; you want pai-ticu- 

 lars respecting them ; and you naturally, and very properly, seek 

 such particulars from those who live on the spot, and who have 

 been familiar with the occurence or circumstance, whatever it may 

 be, from their earliest years. You ask for infoi-mation, I say, but 

 can you always rely upon it when given 1 Have you not often 

 found that the statements of the persons you refer to, without the 

 slightest intention on their part to deceive or to misrepresent the 

 case, rest upon the most imperfect testimony 1 You consider 

 them perhaps as next to worthless, from the circumstance of those 

 who make them being clearly unqpcustomed to look to the bottom 

 of things, and ignorant of the kind of evidence that is wanted to 

 establish a scientific truth. And will not the difficulty of getting 

 at the real fact be increased in proportion to the number of chan- 

 nels through which the statement comes to us, until, in some 

 instances, we come to question with ourselves whether there is the 



