  We consider the harmonic gauge condition in linearized gravity, seen as a
gauge theory for a symmetric tensor field. Once the harmonic gauge condition is
implemented, as customary, according to the Faddeev-Popov procedure, the gauge
fixed action still depends on one gauge parameter. Consequently, the harmonic
gauge appears to be a class of conditions, rather than a particular one. This
allows to give a physical motivation for the covariant harmonic gauge(s), which
emerges when the gravitational perturbation is given a mass term. In fact, for
a particular choice of harmonic gauge, we find a theory of linearized massive
gravity displaying five degrees of freedom, as it should, and which is not
affected by the vDVZ discontinuity, differently from what happens in the
standard Fierz-Pauli theory.
