  The fundamental issues of symmetry related to chirality are discussed and
applied to simple situations relevant to liquid crystals. We show that any
chiral measure of a geometric object is a pseudoscalar (invariant under proper
rotations but changing sign under improper rotations) and must involve
three-point correlations which only come into play when the molecule has at
least four atoms. In general, a molecule is characterized by an infinite set of
chiral parameters. We illustrate the fact that these parameters can have
differing signs and can vanish at different points as a molecule is
continuously deformed into its mirror image. From this it is concluded that
handedness is not an absolute concept but depends on the property being
observed. Within a simplified model of classical interactions, we identify the
chiral parameter of the constituent molecules which determines the macroscopic
pitch of cholesterics.
