  On the basis of the Bethe-Salpeter Equation we developed a covariant
constituent quark model, with confinement implemented by a linear potential and
an instanton induced interaction explaining mass splittings and mixing of
pseudoscalar mesons. In addition this interaction yields a scalar (essentially)
flavour singlet state at approximately 1 GeV, considerably lower in mass than
the corresponding octet states calculated around 1.4 GeV. The validity of the
present approach was checked through various electroweak observables. The
puzzling properties of scalar mesons is briefly discussed.
