  Assuming the validity of the general relativistic description of gravitation
on astrophysical and cosmological length scales, we analytically infer that the
Friedmann-Robertson-Walker cosmology with Einsteinian cosmological constant,
and a vanishing spatial curvature constant, unambiguously requires significant
amount of dark matter. This requirement is consistent with other indications
for dark matter. The same spacetime symmetries that underlie the freely falling
frames of Einsteinian gravity also provide symmetries, which for the spin one
half representation space, furnish a novel construct that carries extremely
limited interactions with respect to the terrestrial detectors made of the
standard model material. Both the `luminous' and `dark' matter turn out to be
residents of the same representation space but they derive their respective
`luminosity' and `darkness' from either belonging to the sector with (CPT)^2 =
+ 1, or to the sector with (CPT)^2 = - 1.
