  Resonances appearing in hadronic scattering processes are described by a
two-phase model. In the one phase, scattering products are observed, whereas
the other phase describes confinement. A so-called ``Resonance-Spectrum
Expansion'' is derived, containing expressions that resemble Breit-Wigner
formulae. This method also provides a straightforward explanation for the
origin of the light scalar mesons without requiring extra degrees of freedom.
