  Precise measurement of the $\pi\pi$-phase shift $\delta^0_0(E)$ at very low
energies would provide, for the first time, the experimental evidence in favour
of or against the existence of a large quark condensate in the QCD vacuum,
which is standardly postulated as the mechanism of the spontaneous breakdown of
chiral symmetry in QCD. The contribution of Da$\phi$ne to this discovery could
be decisive.
