25 2 POPULAR SCIENCE MONTHLY. 



ligious, political, and moral ideas is determined very slowly. "We 

 should not, however, suppose that they are established and vanish 

 with any extreme rapidity. Their evolution is indeed more rapid 

 than that of other ideas, but it follows the same phases. Its history 

 shows that although they address themselves only to the most en- 

 lightened minds, it takes them not less than twenty-five years, and 

 usually much longer, to establish themselves. The clearest of them, 

 the least hypothetical, those most easy to demonstrate, those which 

 would seem least subject to controversy, like the doctrine of the 

 circulation of the blood, have not been accepted in less time. In 

 other respects scientific ideas are established under the influence of 

 the factors we have described as acting with other ideas — affirma- 

 tion, repetition, contagion, and prestige— rand perhaps we may add, 

 since we are dealing with the scientific category, reasoning; but 

 the action of this factor is so weak that we might properly omit it. 

 When it intervenes it is chiefly to refute an accepted idea, not 

 to establish a new one. The new scientific idea is rarely 

 imposed, so far at least as the majority of minds are concerned, 

 by demonstration. It must not be supposed that because a 

 man cultivates science he is released from the yoke of estab- 

 lished dogmas. Scientific dogmas are often the most tyrannical 

 of all. 



The scientific idea is pre-eminently established by the prestige of 

 the man who imposes it, and rarely in any other way.* When 

 Charcot introduced to science the phenomena of animal magnetism, 

 which had been described for more than a century by students whose 

 only fault was that they had no prestige, and whose admirable re- 

 searches had been neglected for that reason by many generations of 

 doctors, shall we suppose that the demonstrations of the professor 

 were what convinced the medical public? ]NTot at all, for the same 

 demonstrations had been repeated thousands of times within a hun- 

 dred years. The conviction was simply the result of the prestige of 

 the expert, who did nothing but introduce into official science a series 

 of phenomena which were perfectly known before him. After hav- 

 ing been established by prestige the scientific idea goes through the 



* It might be objected to this assertion that Darwin, who was without title, claim, or 

 authority, had no prestige when he made his investigations. But it would be easy to 

 answer, first, that his example is almost unique ; and, second, that Darwin's doctrine was 

 supported in England, as soon as it appeared, by men who had much prestige. I am, 

 moreover, not sure that if Darwin had been born in one of the countries where mental worth 

 is exclusively measured by the number of decorations it wears, the immortal book, the 

 Origin of Species, would never have found a reader. The author would soon have been 

 made to understand that, not being an academician or professor, he could only make himself 

 ridiculous by taking up questions which had been long treated by the most illustrious 

 specialists. 



