What are supply clergy?

What are supply
clergy? Are they merely ordained persons who are authorized to use the
costume, magic words and hand motions needed to legitimize  an hour of
worship while the life of the congregation goes along without them quite
well, thank you very much?

That appears
to be the way they are seen and used by more than a few small
congregations without regular clergy.  I think there are several reasons
for it.  First, some supply clergy, mostly retired, see themselves that
way.  They are disinterested in the pastoral care of the people whom
they serve for a few hours, and maybe never again.  The life of the
congregation is of little concern to them.  A bit of extra income and a
chance to exercise their rights of ordination are what it's about.

That fits in
well with congregations who need a clergy person from time to time, but
have no interest in letting some stranger into the intimacy of their
lives together, and, perhaps, some resentment toward larger
congregations with beloved full time pastoral leadership.