  The influence of the in-medium mesons on the effective nucleon mass and in
turn on the equation of state of hot/dense nuclear matter is discussed in the
Walecka model. Due to the self-consistent treatment of couplings between
nucleons and $\sigma $ and $\omega$ mesons, the temperature and density
dependence of the effective hadron masses approaches more towards the Brown-Rho
scaling law, and the compression modulus $K$ is reduced from $550 MeV$ in mean
field theory to an accepted value $318.2 MeV$.
