Ill PASTEUR AND HYDROPHOBIA 155 



direct result of such a position that Pasteur has been 

 able to develop his genius. 



Pasteur himself has not explained what theory he 

 has formed as to the actual nature of the virus of rabies, 

 and as to the way in which his inoculations act, so as 

 to protect an animal from the effects of the virus, even 

 after the virus has been introduced into the system. 

 Possibly he has no precise theory on the subject, but 

 has arrived at his results by an unreasoned exploring 

 method of experimentation. Such a method is not 

 permissible to the ordinary man ; but in the hands of 

 a great thinker and experimentalist it sometimes leads 

 to great results. Charles Darwin once spoke to the 

 present writer of experiments, not dictated by any 

 precise anticipation of a special result, but merely 

 undertaken "to see in a general way what will happen" 

 — as " fool's experiments," and added that he was very 

 fond of such " fool's experiments," and often made 

 them. When the individual who occupies the place 

 of the '' fool " is a man saturated wdth minute know- 

 ledge of the subject on which the experiment is to be 

 tried, it is likely enough that, unconsciously, he frames 

 hypotheses here and there without taking note of what 

 is going on in his own mind, and so is unable to state 

 clearly how he came to make trial of this or that ex- 

 perimental condition. 



Whether Pasteur has worked in this way, trusting 

 to the instinct due to his vast experience, or whether 

 he has reasoned step by step, we do not know. It is 

 nevertheless possible for the bystander to consider the 

 various theories which may be regarded as tending to 



