Calcite, or Iceland Spar, is a transparent form of calcium carbonate. In 1669 Erasmus Bartholin discovered that calcite was doubly refracting; when a naturally-occurring crystal is placed over some writing, two images of the writing are observed. In 1678 Dutch physicist and astronomer Christiaan Huygens observed that visible light passing through a crystal of Iceland spar vibrates in only one plane ( i.e. is plane polarized). In his later publication Traité de la lumière/Treatise on Light (published 1690) which contains Huygens'  famous wave or pulse theory of light, he notes his discovery of the polarization of light, responsible for phenomena such as the double refraction observed with calcite. However, the term "polarized" was not introduced until over 100 years later in the work of Malus.

In 1807 Etienne Louis Malus, a pupil of Charles Fourier, started his investigations into the phenomenon of double refraction with calcite confirming the previous observations of Huygens. In 1808, Malus held a piece of Iceland spar up to some sunlight reflecting off a window of the Luxemburg Palace. To his surprise, he noticed how the intensity varied when he rotated the crystal (the image of the sun is partially polarized upon reflection), and the light beam emanating from the crystal was single, not double. Malus followed this observation with further experiments showing that the ability to polarize light was not restricted to very special crystals but could be present in reflections from any ordinary substance, transparent or opaque, except for polished metals. He later described the light as being "polarized" in his works on polarized light by reflection published in 1809. From these observations, he derived Malus's law that predicts how the intensity of the light transmitted through a polarizer changes when the angle of the transmission is varied (square law).

Several years later in 1811, Francois Arago discovers that some quartz crystals will continuously rotate the electric vector of light (i.e. circular polarization). In 1812, Jean-Baptiste Biot presented a comprehensive theory showing how anisotropic crystalline solids and samples containing an excess of one enantiomer of a chiral molecule rotate the orientation of plane-polarized light (Biot's law). In 1815, he demonstrated that polarized light, when passing through an organic substance, could be rotated clockwise or counterclockwise, dependent upon the optical axis of the material. Further investigation showed that the angle of rotation was a direct measure of the concentration of the substance, which provided a simple mechanism for analyzing saccharine solutions.

Louis Pasteur, a student of Biot, made a series of more famous observations involving solutions of tartaric acid from the tartar deposits in maturing barrels of wine. Tartaric acid was first isolated from potassium tartrate, known to the ancients as tartar, in 1769 by the Swedish chemist Carl Wilhelm Scheele. A second form of this acid, known as para-tartaric acid by Pasteur, was obtained from crude tartar around 1819 by Paul Kestner. In 1828 French chemist Joseph Louis Gay-Lussac coined the name racemic acid (acide racémique, from the Latin racemus, for a bunch of grapes) to describe para-tartaric acid and demonstrated that this racemate had the same chemical composition as tartaric acid. The chirality of tartaric acid was discovered by Biot in 1832, who observed the ability of a tartaric acid solution to rotate polarized light. In 1838, Biot found that para-tartaric acid, unlike its isomer, tartaric acid, was optically inactive. The mystery was that tartaric acid derived by synthesis and para-tartaric acid, were optically inactive even though their reactions and composition were identical in all other respects to natural tartaric acid. Eilhard Mitscherlich examined the sodium ammonium salts of tartaric and para-tartaric acids and found them to be identical in crystalline form except that the former was optically active and the latter was not.

In 1847, Pasteur noticed upon examination of the tiny crystals of tartaric acid that the crystals were hemihedral consistent with previous observations by Mitscherlich. However, further investigation of the para-tartaric acid crystals revealed a property that Mitscherlich had overlooked. In this seminal work, Pasteur noted that two crystalline forms of the sodium-ammonium double salt of para-tartaric acid existed as two asymmetric hemihedral forms that were mirror images of one another. Pasteur manually separated these crystals and noted that the separate solutions, with equivalent concentrations of tartaric acid crystals, rotated linearly polarized light in equal but opposite directions. In addition, when equal parts of the two tartaric acid solutions were combined, no optical rotation was observed. From this observation, Pasteur inferred that optically inactive racemic acid was composed of equal amounts of (+) and (−) tartaric acid. Thereafter, the term racemate was used to describe an optically inactive equimolar mixture of optical isomers. Pasteur was the first to produce a pure sample of levotartaric acid and this was the first demonstration of enantiomers (a pair of optical isomers).

Interestingly, Michael Faraday made his first observation of the magnetically induced optical rotation effect that bears his name several years earlier, in 1845, and Pasteur following on his epochal discovery in 1848 tried in vain to induce chirality by growing crystals in magnetic fields. Lord Kelvin, who is attributed with introducing the word "chirality" (from the Latin chiro, meaning hand) into science, noted that the magnetic rotation was not the source of chirality. The Faraday effect or Faraday rotation is an interaction between light and a magnetic field. The rotation of the plane of polarization is proportional to the intensity of the component of the magnetic field in the direction of propagation of the beam of light. The Faraday effect, also called the Magneto-Optic Effect, was the first experimental evidence that light and magnetism are related. James Clerk Maxwell developed the theoretical basis for that relation, now called electromagnetic radiation, in the 1860's and 1870's.