92 GENERAL VIEW AND BASIS OF SCIENTIFIC KESEARCH. 



subjects to which we feel disposed to listen and give way 

 to authority. A man may repeat a lie until he believes it 

 to be true. Reiterated statements, even in matters which 

 are entirely incapable of demonstration or verification, are 

 a common source of beliefs, and are often considered to 

 be the most strongly established truths ; and any idea, 

 whether true or false, which is often impressed and not 

 contradicted, commonly induces belief, provided it does 

 not appear erroneous on a superficial examination ; men 

 also, in debatable subjects, largely venture to believe what 

 they like, and this is proved by the prevalence of contra- 

 dictory beliefs. A tendency to retain fixed beliefs, irre- 

 spective of their truth or falsity, is also very strong in us, 

 and it consequently requires great mental effort to expel 

 any of our old-established opinions. It is said that when 

 Harvey announced his discovery of the circulation of the 

 blood, no physician, past the age of forty, believed it. but 

 now it would be impossible to find a single physician who 

 disbelieves it. 



Belief, like all our mental acts, is frequently not deter- 

 mined by the intellect, but by the feelings, and may be 

 divided into rational belief and blind credulity. We are 

 all limited by our degrees of mental ability, and there- 

 fore, in the absence of knowledge or proof, blind belief 

 is often a necessity, and may be justified by unavoid- 

 able ignorance ; but that is not a sufficient reason why 

 such ignorance and belief should not be discouraged. All 

 persons are liable to be influenced by those ideas only, 

 irrespective of their truth or falsity, which are within 

 the scope of their comprehension. An unscientific man 

 believes that which he ought not to believe, and fails to 

 believe that which he ought to believe. For instance, he 

 often believes that mysterious or oecult agencies are at 

 work in cases where all the effects are truly explicable by 



