text: Chirality can be traced back to 1812, when physicist Jean-Baptiste Biot found out about a phenomenon called "optical activity." Louis Pasteur, a famous student of Biot's, made a series of observations that led him to suggest that the optical activity of some substances is caused by their molecular asymmetry, which makes nonsuperimposable mirror-images. In 1848, Pasteur grew two different kinds of crystals from the racemic sodium ammonium salt of tartaric acid. He was the first person to separate enantiomeric crystals by hand. In fact Pasteur laid the foundations of stereochemistry and chirality.
  In 1874, Jacobus Henricus van t Hoff came up with the idea of an asymmetric carbon atom. He said that all optically active carbon compounds have an asymmetric carbon atom. In the same year,  Joseph Achille Le Bel only used asymmetry arguments and talked about the asymmetry of the molecules as a whole instead of the asymmetry of each carbon atom. So,        Le Bels idea could be seen as the general theory of stereoisomerism, while van t Hoffs could be seen as a special case (restricted to tetrahedral carbon).
  Soon, scientists started to look into what chiral compounds meant for living things. In 1903, Cushny was the first person to show that enantiomers of a chiral molecule have different biological effects. Lord Kelvin used the word "chiral" for the first time in 1904.