brutal strife where the only possible means of interven-
tion consisted in the suppression of one of the adversaries,
but a gentle strife which one might attempt to direct by
augmenting or diminishing the forces of one of the con-
testants. It was only a question of finding the ground
and the object of the strife, and, for that purpose, he had
the experimental method: it was possible, working with
a single species subject to anthrax, to study bacteridia
of different degrees of virulence; it was possible, with
the same bacteridium, to study different species, or
animals of the same species unequally vaccinated, which
made them, to a certain degree, different animals. We
see what a field of labor opened before him. It is
characteristic of certain discoveries that they suddenly
reveal vast horizons. Pasteur had climbed little by
little to one of those mountain heights from which
a whole new country is visible. He plunges into
it with delight. Let us accompany him. We can
no longer follow him closely and must abandon the his-
torical order. In the first place, we have reached the
latter part of his life and his later conceptions. In the
second place, what interests us is the plan of the edifice,
and not the order in which its different parts have been
erected. If we wish to know which part belongs to
Pasteur himself, which part he has built, we must take
it in the condition in which Pasteur left it, with its
finished parts, with its stones yet unplaced, and with a
brief indication of what the progress of science has
contributed to it.

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