  We show on the basis of an effective theory of QCD that a wide variety of
observables in the hadron world is governed by the chiral symmetry together
with an interplay between the axial anomaly and the explicit symmetry breaking
due to the current quark mass. We also discuss the nature of the chiral
transition at finite temperature and related dynamical phenomena using the
effective Lagrangian. Some phenomenological implications of the small vector
coupling (``vector limit'') at high temperatures are suggested.
