How many such futile incidents, such vain quarrels, traverse the life of a great man! Later on, we only see glory, apotheosis, and the statues in public places; the demi-gods seemed to have marched in triumph towards a grateful posterity. But how many obstacles and oppositions are there to retard the progress of a free mind desirous of bringing his task to a successful conclusion and incited by the fruitful thought of Death, ever present to spirits preoccupied with interests of a superior order? Pasteur looked upon himself as merely a passing guest of those homes of intellect which he wished to enlarge and fortify for those who would come after him. Confronted with the hostility, indifference and scepticism which he found in the members of the Medical Academy, he once appealed to the students who sat on the seats open to the public. “Young men, you who sit on those benches, and who are perhaps the hope of the medical future of the country, do not come here to seek the excitement of polemics, but come and learn Method.” His method, as opposed to vague conceptions and _a priori_ speculations, went on fortifying itself day by day. Artificial attenuation, that is, virus modified by the oxygen of air, which weakens and abates virulence; vaccination by the attenuated virus--those two immense steps in advance were announced by Pasteur at the end of 1880. But would the same process apply to the microbe of charbon? That was a great problem. The vaccine of chicken-cholera was easy to obtain; by leaving pure cultures to themselves for a time in contact with air, they soon lost their virulence. But the spores of charbon, very indifferent to atmospheric air, preserved an indefinitely prolonged virulence. After eight, ten or twelve years, spores found in the graves of victims of splenic fever were still in full virulent activity. It was therefore necessary to turn the difficulty by a culture process which would act on the filament-shaped bacteridium before the formation of spores. What may now be explained in a few words demanded long weeks of trials, tests and counter tests. In neutralized chicken broth, the bacteridium can no longer be cultivated at a temperature of 45° C.; it can still be cultivated easily at a temperature of 42° C. or 43° C., but the spores do not develop. “At that extreme temperature,” explains M. Chamberland, “the bacteridia yet live and reproduce themselves, but they never give any germs. Thenceforth, when trying the virulence of the phials after six, eight, ten or fifteen days, we have found exactly the same phenomena as for chicken-cholera. After eight days, for instance, our culture, which originally killed ten sheep out of ten, only kills four or five; after ten or twelve days it does not kill any; it merely communicates to animals a benignant malady which preserves them from the deadly form.