With every measure that physicians may take to prevent the germs of diseases from coming, in spite of all the success that they will have there will be a greater failure; for even if the actual germ is destroyed, it exists, its family exists, somewhere. Besides, the body which has once become the abode of that particular germ has become a receptacle of the same germ. If the physician destroys the germ of disease from the body of an individual, that does not mean that he destroys it from the universe.