  The instanton representation of Plebanski gravity provides as equations of
motion a Hodge self-duality condition and a set of `generalized' Maxwell's
equations, subject to gravitational degrees of freedom encoded in the initial
value constraints of general relativity. The main result of the present paper
will be to prove that this constraint surface is preserved under time
evolution. We carry this out not using the usual Dirac procedure, but rather
the Lagrangian equations of motion themsleves. Finally, we provide a comparison
with the Ashtekar formulation to place these results into overall context.
