Louis Pasteur

THE LEGEND OF PASTEUR S3
chemical properties of crystals. The elegance and precision of
this field of research appealed to the neat and orderly Pasteur.
Moreover, it soon provided him with a specific question worthy
of his industry and imagination. He had read in the school library
a recent note in which the celebrated German crystallographer
and chemist Mitscherlich had stated that the salts of tartaric and
paratartaric acids, although identical in chemical composition and
properties, differed in their ability to rotate the plane of polarized
light. This anomaly had remained in Pasteur's mind as an obsess-
ing question, and it was to clarify it that he undertook the study
which led him to recognize that paratartaric acid was, in reality,
a mixture of two different tartaric acids possessing equal optical
activity, except for the fact that one (the right or dextro form)
rotated a polarized beam of light to the right, whereas the other
(the left or levo form) rotated light to the left. The genesis and
significance of this discovery will be discussed in succeeding
chapters. Suffice it to point out here that Pasteur had demon-
strated, with one stroke, independence of mind in questioning
the statement of a world-famous scientist, imagination in recog-
nizing the existence of an important problem, and experimental,
genius in dealing with it. He had exhibited extraordinary power
of detailed observation, a superb competence in planning the
strategy and tactics of his experimental attack, tireless energy
and meticulous care in its execution.
Pasteur had become interested in crystal structure before realiz-
ing that this study would lead him into questions
of immense
theoretical
significance, but the implications of his findings soon
became apparent to him. That he found the problem worthy of
his metal is obvious from the enthusiasm displayed in a letter
to his friend Chappuis: "How many times I have regretted that
we did not both undertake the same studies, that of physical
sciences! We who so often used to speak of the future, how little
we understood! What beautiful problems we would have under-
taken, we would undertake today, and what could we have not
solved, united in the same ideas, the same love of science, the
same ambition? I wish that we were again twenty and that the