196 PASTEUR 



cases to your special and personal labours, there 

 are already a number of these pernicious disor- 

 ders of the causes of which we have a com- 

 plete knowledge. 



"Felix qui potuit rerum cognoscere causas. 



"This knowledge has already perfected in a 

 surprising fashion the diagnosis of these 

 scourges of the human race, and has pointed 

 out the path which must be followed in their 

 prophylactic and curative treatment. On this 

 path your fine discoveries of the attenuation 

 and reinforcement of viruses and preventive 

 inoculations serve and will always continue to 

 serve as guiding stars. 



"As a brilliant illustration, I may refer to 

 your services in regard to hydrophobia. Their 

 originality is so striking, both in respect to 

 pathology and to therapeutics, that in the be- 

 ginning many physicians were mistrustful of 

 you. 



" 'Is it possible/ they said to me, 'that a man 

 who is neither a physician nor a biologist can 

 instruct us after this fashion regarding a dis- 



