  I discuss the mass parameters appearing in the gauge theory of the strong
interactions, concentrating on the two flavor case. I show how the effect of
the CP violating parameter $\theta$ is simply interpreted in terms of the state
of the {\ae}ther via an effective potential for meson fields. For degenerate
flavors I show that a first order phase transition is expected at $\theta=\pi.$
I speculate on the implications of this structure for Wilson's lattice
fermions.
