  We comment on the recent paper (hep-lat/0005006) by Isgur and Thacker on the
origin of the OZI rule in QCD. We show that instantons explain the sign and
magnitude of the observed OZI-violating amplitude in all mesonic channels, not
just in the $\eta'$ channel. We comment on the role of instantons in hadronic
spectroscopy and the relation between instantons and the large $N_c$ limit of
QCD.

High Energy Physics - Lattice;High Energy Physics - Phenomenology