  Although there are phenomenological indications that the low-energy constants
in the chiral lagrangian may be understood in terms of a finite number of
hadronic resonances, it remains unclear how this follows from QCD. One of the
arguments usually given is that low-energy constants are associated with chiral
symmetry breaking, while QCD perturbation theory suggests that at high energy
chiral symmetry is unbroken, so that only low-lying resonances contribute to
the low-energy constants. We revisit this argument in the limit of large Nc,
discussing its validity in particular for the low-energy constant L8, and
conclude that QCD may be more subtle that what this argument suggests. We
illustrate our considerations in a simple Regge-like model which also applies
at finite Nc.
