The path-integral formulation of Reggeon field theory at zero transverse dimension, $D=0$, is examined. We point out the necessity of breaking the classical permutation symmetry and argue that this is accomplished by enforcing quantum stability conditions in a nonperturbative path-integral formalism. By breaking the permutation symmetry, we show that the tunneling effect for the $D=0$ theory when the bare Pomeron intercept is greater than one is not due to classical configurations; instead, tunneling comes about by a certain mixture of quantum and classical configurations. Our picture naturally leads to the instanton vacuum solution for the $D\ensuremath{\ne}0$ supercritical region advocated by White.