Louis Pasteur Quote

Every chemical substance, whether natural or artificial, falls into one of two major categories, according to the spatial characteristic of its form. The distinction is between those substances that have a plane of symmetry and those that do not. The former belong to the mineral, the latter to the living world.

Pasteur Vallery-Radot (ed.), Oeuvres de Pasteur (1922–1939), Vol. 1, 331. Quoted in Patrice Debré, Louis Pasteur, trans. Elborg Forster (1994)