Whatever your career may be, do not let yourselves become tainted by a deprecating and barren scepticism.
Louis PasteurAre the atoms of the dextroacid (tartaric) grouped in the spirals of a right-hand helix or situated at the angles of an irregular tetrahedron, or arranged in such or such particular unsymmetrical fashion? We are unable to reply to these questions. But there can be no reason for doubting that the grouping of the atoms has an unsymmetrical arrangement with a non-superimposable image. It is not less certain that the atoms of the laevo-acid realize precisely an unsymmetrical arrangement of the inverse of the above.
Louis PasteurVirulence appears in a new light which cannot but be alarming to humanity; unless nature, in her evolution down the ages (an evolution which, as we now know, has been going on for millions, nay, hundreds of millions of years), has finally exhausted all the possibilities of producing virulent or contagious diseases - which does not seem very likely.
Louis Pasteur