  We develop the mathematics needed to treat the interaction of geometry and
stress at any isotropic spacetime singularity. This enables us to handle the
Einstein equations at the initial singularity and characterize allowed general
relativistic stress-energy tensors. Their leading behaviors are dictated by an
initial hypersurface conformal embedding. We also show that an isotropic Big
Bang determines a canonical non-singular metric on and about the initial
hypersurface as well as a cosmological time. This assigns a volume and energy
to the initial point singularity.
