86 PASTEUR: THE HISTORY OF A MIND 



a question which, with just reciprocity, these same studies 

 permitted him to solve. Whence come the ferments? 

 Are they organized spontaneously at the expense of 

 dead organic matter? Or, do they come in the regular 

 ways from organisms like themselves, and from pre- 

 existing germs? Here we have a question which had 

 been asked very often, ever since men had begun to reflect, 

 and which had been solved in very different ways. Pas- 

 teur, himself, at the close of his studies on crystallog- 

 raphy, had been very undecided, and I think also very 

 indifferent regarding the answer. He had no precon- 

 ceived ideas: he would accept the results of experi- 

 mentation. But at the point to which the study of 

 fermentations had led him, he could no longer believe 

 in spontaneous generation: it is too far removed from 

 the idea of specificity, which he had just introduced 

 into science. Everywhere around us the idea of species 

 accompanies the idea of continuance by the germ cell, 

 and it would be very astonishing if this order were changed 

 in the world of the infinitely little. 



The ancients believed in the spontaneous generation of 

 eels from the ooze of rivers, and in that of bees in the 

 entrails of a dead bull. But these were the ideas of a 

 child who had never lived in the face of the progress of 

 knowledge. For a long time people had believed in the 

 spontaneous generation of worms in putrefying meat, 

 because in this case the experiment is more difficult or 

 the observation is more delicate, and a Redi was neces- 

 sary to demonstrate that these worms come from eggs 

 laid by flies, and that one would no longer see them in a 

 piece of meat which was protected by a simple layer of 

 gauze. It is true that this piece of meat continued to 

 putrefy, to decay, and to nourish, no longer worms but 

 confused tribes of microscopic organisms. As long as 

 it was the belief that fermentation and putrefaction oc- 



