  The quark-level linear sigma model is employed to compute a variety of
electromagnetic and weak observables of light mesons, including pion and kaon
form factors and charge radii, charged-pion polarizabilities, semileptonic weak
$K_{\ell3}$ decay, semileptonic weak radiative pion and kaon form factors,
radiative decays of vector mesons, and nonleptonic weak $K_{2\pi}$ decay. The
agreement of all these predicted observables with experiment is striking. In
passing, the tight link between the linear sigma model and vector-meson
dominance is shown. Some conclusions are drawn on the linear sigma model in
connection with lattice and renormalization-group approaches to QCD.
