  We revisit several aspects of the interaction of self-gravitating, slowly
varying sources with their own emitted radiation within the context of
post-Newtonian approximation to General Relativity. We discuss and clarify the
choice of boundary conditions of Green's functions used to determine
conservative potentials, and the interplay between the so-called near and far
zones, as well as the relation between far zone ultra-violet divergences and
emitted power. Both near and far zone contributions are required for the
computation of the conservative dynamics. Within a field-theory approach we
rederive far-zone self-energy processes, known as tail and memory effects,
generalising the calculation of their divergent part to arbitrary order in the
post-Newtonian expansion.
