  Nuclear Field Theory of structure and reactions is confronted with
observations made on neutron halo dripline nuclei, resulting in the prediction
of a novel (symbiotic) mode of nuclear excitation, and on the observation of
the virtual effect of the halo phenomenon in the apparently non-halo nucleus
$^7$Li. This effect is forced to become real by intervening the virtual process
with an external (t,p) field which, combined with accurate predictive abilities
concerning the absolute differential cross section, reveals an increase of a
factor 2 in the cross section due to the presence of halo ground state
correlations, and is essential to reproduce the value of the observed $d
\sigma(^7$Li(t,p)$^9$Li)/d$\Omega$.
