FERMENTS, FERMENTATIONS, AND LIFE. 63 



Neither patient observations, nor minute experiments, nor 

 profound reasonings, have been wanting ; yet some still be- 

 lieve that these little bodies grow, by spontaneous genera- 

 tion, within fermentable liquids, while others assert, and 

 profess to have proved, that they come from germs con- 

 tained in the air. Certainly, the former opinion involves 

 nothing contradictory nor impossible. Those who reject 

 it by begging the question, in the name of some unknown, 

 mystical doctrine of life, do not even deserve to be listened 

 to in the investigation. It might possibly have occurred 

 that organized beings should be produced, complete at all 

 points, in a medium deprived of organization ; yet experi- 

 ment proves that this does not occur. We must, then, ac- 

 cept the other opinion the panspermist doctrine that is to 

 say, we must concede that the germs of microscopic animals 

 and vegetables, with which so many fermentations and 

 putrefactions are connected, exist in the air. This is one 

 of the conclusions, and perhaps the most legitimate and 

 most fertile one, of Pasteur's striking studies. 



He deserves the glory of it precisely because he has not 

 priority in it. In truth, the originator of this idea only 

 had, and could only have, a dim intuition of it. He could 

 measure neither its importance nor its consequences. The 

 importance and the results of a great idea, whatever it may 

 be, only become apparent when, after undergoing a cer- 

 tain evolution, it has gained the precision, certitude, and 

 establishment, that nothing but long experience can confer 

 upon it. A conception must have acquired some age in 

 science to wear a fixed authority, and bestow fame on those 

 who comprehend, and cause to be comprehended, all its 

 grandeur and power. The circulation of the blood had 

 long been seen by glimpses, in the schools of physiology, 

 when Harvey gave it complete and vigorous demonstration. 

 Gravitation had long invited research, and suggested pre- 

 sentiment, before Newton drew its perfect system. So, 



