146 PASTEUR: THE HISTORY OF A MIND 



the cause of the disease. That is the idea divested of all 

 its trappings an idea reached ordinarily only after 

 one has made the tour of ideas much more complicated. 

 In fact, as we shall see, Pasteur reached this conclusion 

 only, so to speak, in spite of himself, and after two years 

 of study. 



He was, it seems, more disposed to believe at this 

 moment that the disease, whatever it might be, could 

 by modifying the fluids of the body prepare the soil 

 for this or that microbe, which was then according to the 

 case, either the result of the disease, or the visible evi- 

 dence of it, or the beginning of a new disease. We shall 

 see later that these notions are not as exclusive of the 

 other idea as one might at first sight beheve them to be. 

 In all cases, they ended with a repercussion of the microbe 

 on its host, and it was for this reason that Pasteur main- 

 tained for so long a time the relations between the phy- 

 siology of the ferments and that of the higher animals. 

 Thus we have seen him liken the red blood-corpuscle 

 to the acetic ferment which, like the latter, can take 

 the oxygen from the air and carry it, endowed with a more 

 powerful activity, to the combustible substance. 



But when there was raised the question of going farther 

 and of actually coming into contact with the higher 

 animals, Pasteur hesitated. He was not a physiologist. 

 To no purpose did we go to hear the course of Claude 

 Bernard, where he took notes feverishly. It would have 

 been necessary for him to become a new soul, and he had 

 neither the time for it nor the patience. The insist- 

 ance of Dumas had just placed him face to face with 

 an experience which he both desired and dreaded, and 

 if his self-distrust had made him hesitate, at the first 

 encounter, in reality, the attraction for the unknown and 

 a certain interior voice urged him to accept. 



Consequently, his decision was soon made. After 



