  Reconstructed from lensing tomography, the evolution of the dark matter
density field in the well-understood linear regime can provide
model-independent constraints on the growth function of structure and the
evolution of the dark energy density. We examine this potential in the context
that high-redshift cosmology has in the future been fixed by CMB measurements.
We construct sharp tests for the existence of multiple dark matter components
or a dark energy component that is not a cosmological constant. These
functional constraints can be transformed into physically motivated model
parameters. From the growth function, the fraction of the dark matter in a
smooth component, such as a light neutrino, may be constrained to a statistical
precision of sigma(f)= 0.0006 fsky^{-1/2} by a survey covering a fraction of
sky fsky with redshift resolution dz=0.1. For the dark energy, a
parameterization in terms of the present energy density Omega_{DE}, equation of
state w and its redshift derivative w', the constraints correspond to
sigma(w)=0.016 fsky^{-1/2} and a degenerate combination of the other two
parameters. For a fixed Omega_{DE}, sigma(w') = 0.046 fsky^{-1/2}; for
Omega_{DE} marginalized, sigma(w') = 0.069 fsky^{-1/2}.
