  We present a light-front determination of the pionic contribution to the
nucleon self-energy, $\Sigma_\pi$, to second-order in pion-baryon coupling
constants that allows the pion-nucleon vertex function to be treated in a
model-independent manner constrained by experiment. The pion mass $\mu$
dependence of $\Sigma_\pi$ is consistent with chiral perturbation theory
results for small values of $\mu$ and is also linearly dependent on $\mu$ for
larger values, in accord with the results of lattice QCD calculations. The
derivative of $\Sigma_\pi$ with respect to $\mu^2$ yields the dominant
contribution to the pion content, which is consistent with the
$\bar{d}-\bar{u}$ difference observed experimentally in the violation of the
Gottfried sum rule.
