  If high temperature cuprate superconductivity is due to electronic
correlations, then the energy difference between the normal and superconducting
states can be expressed in terms of the occupied part of the single particle
spectral function. The latter can, in principle, be determined from angle
resolved photoemission (ARPES) data. As a consequence, the energy gain driving
the development of the superconducting state is intimately related to the
dramatic changes in the photoemission lineshape when going below Tc. These
points are illustrated in the context of the "mode" model used to fit ARPES
data in the normal and superconducting states, where the question of kinetic
energy versus potential energy driven superconductivity is explored in detail.
We use our findings to comment on the relation of ARPES data to the
condensation energy, and to various other experimental data. In particular, our
results suggest that the nature of the superconducting transition is strongly
related to how anomalous (non Fermi liquid like) the normal state spectral
function is, and as such, is dependent upon the doping level.
