to those who
may know comparatively little of his works and teachings. Pierre Charles
Alexandre Louis, at the age of forty-seven, as I recall him, was a tall,
rather spare, dignified personage, of serene and grave aspect, but with
a pleasant smile and kindly voice for the student with whom he came
into personal relations. If I summed up the lessons of Louis in two
expressions, they would be these; I do not hold him answerable for the
words, but I will condense them after my own fashion in French, and then
give them to you, expanded somewhat, in English:

Formez toujours des idees nettes.
Fuyez toujours les a peu pres.

Always make sure that you form a distinct and clear idea of the matter
you are considering.

Always avoid vague approximations where exact estimates are possible;
about so many,--about so much, instead of the precise number and
quantity.

Now, if there is anything on which the biological sciences have prided
themselves in these latter years it is the substitution of quantitative
for qualitative formulae. The "numerical system," of which Louis was
the great advocate, if not the absolute originator, was an attempt
to substitute series of carefully recorded facts, rigidly counted and
closely compared, for those never-ending records of vague, unverifiable
conclusions with which the classics of the healing art were overloaded.
The history of practical medicine had been like the story of the
Danaides. "Experience" had been, from time immemorial, pouring its
flowing treasures into buckets full of holes. At the existing rate of
supply and leakage they would never be filled; nothing would ever be
settled in medicine. But cases thoroughly recorded and mathematically
analyzed would always be available for future use, and when accumulated
in sufficient number would lead to results which would be trustworthy,
and belong to science.

You young men who are following the hospitals hardly know how much you
are indebted to Louis. I say nothing of his Researches on Phthisis or
his great work on Typhoid Fever. But I consider his modest and brief
Essay on Bleeding in some Inflammatory Diseases, based on cases
carefully observed and numerically analyzed, one of the most important
written contributions to practical medicine, to the treatment of
internal disease, of this century, if not since the days of Sydenham.
The lancet was the magician's wand of the dark ages of medicine. The old
physicians not only believ