  I discuss several aspects of CP non-invariance in the strongly interacting
theory of quarks and gluons. I use a simple effective Lagrangian technique to
map out the region of quark masses where CP symmetry is spontaneously broken. I
then turn to the possible explicit CP violation arising from a complex quark
mass. After summarizing the definition of the renormalized theory as a limit, I
argue that attempts to remove the CP violation by making the lightest quark
mass vanish are not well defined. I close with some warnings for lattice
simulations.
