150 PIONEERS OF EVOLUTION. 



proofs what wholly untrustworthy observers scien- 

 tific specialists can be outside their own domain. As 

 the writer has remarked elsewhere, minds of this 

 type must be built in water-tight compartments. 

 They show how, even in the higher culture, the force 

 of a dominant idea may suspend or narcotize the 

 reason and judgment, and contribute to the rise and 

 spread of another of the epidemic delusions of which 

 history supplies warning examples. 



They also show that man's senses have been his 

 arch-deceivers, and his preconceptions their abettors, 

 throughout human history; that advance has been 

 possible only as he has escaped through the disci- 

 pline of the intellect from the illusive impressions 

 about phenomena which the senses convey. Upon 

 this matter the words of the late Dr. Carpenter may 

 be quoted, words the more weighty because they are 

 the utterance of a man whose philosophy was influ- 

 enced by deep religious convictions: "With every 

 disposition to accept facts when I could once clearly 

 satisfy myself that they were facts, I have had to 

 come to the conclusion that whenever I have been 

 permitted to employ such tests as I should employ 

 in any scientific investigation, there was either inten- 

 tional deception on the part of interested persons, or 

 else self-deception on the part of persons who were 

 very sober-minded and rational upon all ordinary 

 affairs of life." He adds further: " It has been my 

 business lately to inquire into the mental condition 

 of some of the individuals who have reported the 



