134 PASTEUR: THE HISTORY OF A MIND 



tion, that is to say one of the maladies to which wine is 

 constantly exposed, is exclusively the work of a micro- 

 organism. But there are many other diseases which 

 invade wines with more or less rapidity. The wines of 

 Bordeaux turn, those of Burgundy become hitter, the 

 wines of Champaigne become ropy. At this time, the 

 Phylloxera had not yet made its appearance, and many 

 persons had caves; but there was no cave where a malady 

 of the wine did not appear from time to time, and did 

 not cause losses, which were often grievous. 



Upon that point, the ideas of Liebig shed no great light. 

 According to them, the wine was constantly in move- 

 ment, at work; those wines which preserved themselves 

 intact, and were called de garde, reached the end of 

 fermentation with a certain state of equilibrium between 

 their sugar and their organic matter serving as ferment; 

 these two elements were equally exhausted. If there 

 had been too little ferment in the beginning, a portion of 

 the sugar remained unchanged, and the wine was sweet, 

 that is to say incomplete. If there had been too little 

 sugar, on the contrary, some ferment remained which 

 continued to work upon the substance and to produce 

 therein vitiations of the taste. This explanation, so 

 beautifully symmetrical, had seduced people's minds, 

 and the reader found it paraphrased in all the books on 

 the subject. As to a remedy, it did not give any, or at 

 least it had not done so. 



For Pasteur, on the contrary, these ideas had no mean- 

 ing. He was sure that the activity of the yeast was 

 arrested after having transformed the sugar, and that 

 it could act neither upon the alcohol which it had 

 formed, nor upon the other elements of the wine. In 

 that he was deceived, for we have seen since that the 

 yeast can destroy in time the glycerin which it has 

 produced, just as the mycoderma of the vinegar burns the 



