• Pasteur;
  • molecular chirality;
  • spontaneous resolution;
  • dissymmetry

Pasteur's chemical and crystallographic work is described. The article commences with a brief overview of related science (chemical structure, crystallography, optical activity) before and after 1848, the year of the discovery of molecular chirality and spontaneous resolution. Concerning this discovery, three separate and varying reports are described. These are: (i) the publications in the scientific literature, (ii) the early (auto)biographies and (iii) Pasteur's handwritten laboratory notebooks. The three versions give differing views on the topic. Subsequently all of Pasteur's crystallographic and chemical work is passed in review, a topic very rarely broached. Pasteur's view in later life on this part of his work is examined. The article concludes with a discussion of the term dissymmetry used by Pasteur.