12 LOUIS PASTEUE. 



their starting-point the note of Mitscherlich and the 

 memoir of M. de la Provostaye have appeared to me, 

 whenever I tried to master them, difficult of access. 

 Ah,' I added, ' you would have done well, out of con- 

 sideration for those who love to speak of your labours, 

 had you made no discoveries in this field.' 



Pasteur, with a mixture of indignation and indul- 

 gence, replied : ' Is it possible that you have not 

 discerned the grand horizons that lie behind these 

 researches in physics and molecular optics ? If I 

 have a regret, it is that I did not follow out this path. 

 Less rough than it at first sight appears, it would, I 

 am convinced, have led to the most important dis- 

 coveries. By a sudden turn it threw me unexpectedly 

 upon the subject of fermentation, and fermentation 

 led me to the study of diseases ; but I still continue 

 to lament that I have never had time to retrace my 

 steps.' 



Then, with a simplicity of exposition in which one 

 recognised the teacher who had always endeavoured 

 to place his ideas within the range of his hearers, he 

 said 



' If you picture to yourself all the bodies in nature 

 mineral, animal, or vegetable, and consider even 

 the objects formed by the hands of man, you will see 

 that they divide themselves into two great categories. 

 The one has a plane of symmetry and the other has 

 not. Take, for instance, a table, a chair, a playing 



