Huxley said that Pasteur's work on fermentation alone saved France more than enough to pay the loss of the FranceGerman war.
Of Pasteur’s life, apart from his work, but little is to be said; for his life is emphatically his work. A normally idle and pleasure-loving childhood passed into an adolescence of rare industry and a maturity of entire self-devotion; and the truant schoolboy developed into a Scientific philosopher whose breadth of outlook, depth of insight and acuteness of conjecture–to be afterward verified by careful observation and minute investigation–have had results as important as those of the spectroscope and the polariscope. Much as the world owes to Darwin for that grand truth of evolution which shows life as an harmonious whole and makes the future stride possible by the past advance, it owes as much to Pasteur for his discovery of those microscopic agents, those forces of the infinitely little, by which organic changes are brought about and the processes of disease and disintegration are carried on.
Pasteur’s first work was in the field of molecular physics, and the important discovery of molecular dissymmetry was originally due to the note which Mitscherlich sent to the Academy of Sciences. This note stated that the,
This difference of behavior of polarized light made Pasteur infer that the identity of the two salts was only apparent, not real, and that further research would reveal molecular discrepancies of an important kind. He verified his belief; but somewhat in a different way from that which he had expected. He expected to find, and he found, that the crystalline forms of the tartrates, and all their chemical compounds, have not what mathematicians call a “plane of symmetry”–that is, are not among those objects which, when placed before a mirror, have a superposable image identical with themselves, and are therefore dissymmetrical; while, on the other hand, he believed that the paratartrates would have this plane of symmetry, this superposable image, and be therefore symmetrical. He found, instead, that all the paratartrates were dissymmetrical like the tartrates; but certain crystals possessed this dissymmetry in one sense and other crystals in an opposite sense.
Then by saturating racemic or paratartaric acid with soda and ammonia he procured crystals of inverse dissymmetry–the one set turning the plane of polarized light to the right (dextro-racemic acid), the other to the left (lævo-racemic acid). Of these the left-handed crystal was the new discovery, though Biot had already proved the existence of this double property in rock-crystal. This inversion is due to certain minute facets which, in the one crystal, are ranged along a right-handed, and in the other along a left-handed, spiral.
More, again, than this, Pasteur proved that all the crystalline products of inorganic matter have this superposable image, and are consequently symmetrical; while all vegetable and animal products, all crystals produced from organic and living beings, are dissymmetrical. The explanation he gives of the apparent contradiction to this law, in the existence in living creatures of certain substances like oxalic acid, formic acid, etc., which do not act on polarized light, and of which the crystals do not show a trace of dissymmetry, is an example of his acute power of classification. It is, he says, because these substances are the products of excretion rather than substances essential to animal and vegetable life, hence are,