Chiral compounds consist of optically active, non-superimposable stereoisomers that are mirror images of each other (enantiomers.) This geometric property is termed chirality (from the ancient Greek for “hand”). Just as right and left hands are not superimposable, stereo-isomeric chiral molecules have the same chemical formulas but one stereoisomer is not superimposable with its mirror image. The mirror image forms of a chiral molecule can have radically different properties. The critical importance of being able to separate chiral molecules into their “right hand” and “left hand” enantiomers is illustrated by the thalidomide disaster of the late 1950s and early 1960s. The use of thalidomide, which consists of a racemic mixture of (R) (curative) and (S) (teratogenic i.e., an agent or factor which causes malformation of an embryo) enantiomers, resulted in a medical tragedy affecting an estimated 10,000 babies born with severe deformities.