  The external-field QCD Sum Rules method is used to evaluate the coupling
constant of the light isoscalar-scalar meson (``$\sigma$'' or \epsilon) to the
nucleon. The contributions that come from the excited nucleon states and the
response of the continuum threshold to the external field are calculated. The
obtained value of the coupling constant is compatible with the large value
required in one-boson exchange potential models of the two-nucleon interaction.
