  A new mechanism for spontaneous breaking of flavour symmetry is demonstrated.
An exactly flavour symmetric model with degenerate bare nonets and with
sufficiently strong tri-linear meson couplings is shown to lead to
self-consistency equations which are unstable. Instead there exists a stable
solution, which break flavour symmetry spontaneously in the mass spectrum. For
a C-degenerate meson spectrum the stable mass spectrum obeys the
Okubo-Zweig-Iizuka (OZI) rule and the approximate equal spacing rule.
