CHAPTER NINE 



DIFFICULTIES 



" Error is all around us and creeps in at the least oppor- 

 tunity. Every method is imperfect." — Charles Nicolle. 



Mental resistance to new ideas 



WHEN the great discoveries of science were made they 

 appeared in a very different light than they do now. 

 Previous ignorance on the subject was rarely recognised, for 

 either a blind eye was turned to the problem and people were 

 scarcely aware of its existence, or there were weU accepted 

 notions on the subject, and these had to be ousted to make way 

 for the new conceptions. Professor H. Butterfield points out 

 that the most difficult mental act of all is to re-arrange a familiar 

 bundle of data, to look at it differently and escape from the 

 prevailing doctrine.^" This was the great intellectual hurdle 

 that confronted such pioneers as Galileo, but in a minor form 

 it crops up with every important original discovery. Things 

 that are now quite easy for children to grasp, such as the 

 elementary facts of the planetary system, required the colossal 

 intellectual feat of a genius to conceive when his mind was 

 already conditioned with AristoteHan notions. 



WiUiam Harvey's discovery of the circulation of the blood 

 might have been relatively easy but for the prevailing beliefs 

 that the blood ebbed and flowed in the vessels, that there were 

 two sorts of blood and that the blood was able to pass from 

 one side of the heart to the other. His first cause for dissatisfac- 

 tion with these doctrines was his finding of the direction in 

 which the valves faced in the veins of the head and neck — a 

 small stubborn fact which the current hypothesis did not fit. He 

 dissected no fewer than eighty species of animals including rep- 

 tiles, crustaceans and insects, and spent many years on the investi- 

 gation. The big difficulty in establishing the conception of the 

 circulation was the absence of any visible connection between 



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