  We use over-improved stout-link smearing to investigate the presence and
nature of instantons on the lattice. We find that smearing can remove
short-range effects with little damage to the long-range structure of the gauge
field, and that after around 50 sweeps this process is complete. There are more
significant risks for very high levels of smearing beyond 100 sweeps. We are
thus able to produce gauge configurations dominated by instanton effects. We
then calculate the overlap quark propagator on these configurations, and thus
the non-perturbative mass function. We find that smeared configurations
reproduce the majority of dynamical mass generation, and conclude that
instantons are primarily responsible for the dynamical generation of mass.
