the ideas of Virchow in pathology. If Fate had willed
that he should not finish his task, that he should suc-
cumb to the hemiplegia which attacked him at the time
of his studies on silkworms, some other scientific man
would have come, a Koch for example, for whom Pasteur
would have been a precursor because he would have
pointed out the way and left behind him the means of
following it. His pathological work was the develop-
ment and the compliment of his work upon the fermen-
tations. But Pasteur had no precursor in the proper
sense of this word, that is to say, he did not develop
and extend the ideas of anyone else. He remains the
equal of many when he demonstrates the bacterial origin
of anthrax or of other diseases. Where he is without
equal is when he discovers the attenuation of viruses,
and when he introduces into science that fertile no-
tion which allows us to act upon a disease by acting,
not upon the sick person, as up to that time one had
been in the habit of doing, but upon the pathological
bacterium.

What renders his history particularly interesting at
this period, is that we can follow the stages of his
progress. As we have seen, he had had for a long time
the desire to enter into pathology. He was led to it
by that secret force of things the elements of which we
have just analyzed. He showed himself an eager student
of medical works and after having borrowed from them
certain words, as we have seen, at the beginning of his
studies upon the disease of silkworms, he began to pene-
trate into things. From this stage his choice was nar-
rowly restricted. He had read and meditated on the
works of Jenner upon vaccine, those which Coze
and Feltz had just published. But what interested him
most of all were the studies which Davaine was pursuing
at this time upon the anthrax bacteridium.

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