  After giving a short introduction to the Nambu-Jona-Lasinio model with an
anomaly term, we show the importance of the scalar-scalar correlation in the
low-energy hadron dynamics, which correlation may be summarized by a
scalar-isoscalar meson, the sigma meson. The discussion is based on the chiral
quark model with the sigma-meson degrees of freedom. Possible experiments are
proposed to produce the elusive meson in a nucleus and detect it. In relation
to a precursory soft mode for the chiral transition, the reason is clarified
why the dynamic properties of the superconductor may be described by the
diffusive time-dependent Ginzburg-Landau (TDGL) equation. We indicate the
chiral symmetry plays a significant role also in nuclei; one may say that the
stability of nuclei is due to the chiral symmetry of QCD.
