300 Pasteur: the history of a mind 



scientists are still working, and on which the last word 

 has not been said. 



On what depends that immunity which vaccinated 

 animals possess, which is also possessed by animals nat- 

 urally resistant to certain diseases fatal to other species? 

 Why does the cow contract anthrax less easily than the 

 sheep of Beauce, and the sheep of Algiers less easily 

 still than the cow? Why is man not attacked by certain 

 diseases of the domestic animals, and inversely? Here 

 were questions which, yesterday premature and auda- 

 cious, could now be stated and become the object of an 

 experimental study. In a word, it was not alone the 

 mechanism of the disease which ought to be the subject 

 matter for experiment, but also the mechanism of health, 

 that is to say, the entire physiology of the living creature, 

 and already one could foresee that Pasteur and Claude 

 Bernard were about to join hands to contribute to a 

 deeper conception of the life of the cell. 



The new idea which Pasteur brought into this study 

 was the idea of strife between two cells or two groups 

 of cells, and here I seem to be advancing a daring prop- 

 osition, to such a degree does the idea of strife form a 

 part of the old conception of disease and even, gener- 

 ally, of the appearance of the sick person. During the 

 metaphysical period of pathology, when the direction 

 of life was attributed to a vital force superposed on all 

 the organs, one had been led to imagine the disease as 

 a distinct entity, entering into combat with the vital 

 force in the organism.^ When, through the progress 

 of physiology, the vital force was, so to speak, reduced 

 to an infinite number of cellular lives, each having its 



1 This is the theory of homeopathy. If the proper drup; is administered, 

 that is, one having a greater affinity for the entity of the disease than the 

 latter has for the body, then the drug-spirit and tlie cUsease-spirit will 

 combine and the patient will return to his normal condition. Vide 

 Hempel's Materia IMedica. 7'rs. 



