science has explained the optical delusion, and shown the
physiological state in which such apparitions become visible. Ridicule
will not do it. Disproof will not do it. So long as men feel that
there is a spirit-world, and so long as to some the impression is
vivid that they have seen it, you spend your rhetoric in vain. You
must show the truth that lies below the error.

The principle we gain from this is that you cannot overthrow falsehood
by negation, but by establishing the antagonistic truth. The
refutation which is to last must be positive, not negative. It is an
endless work to be uprooting weeds: plant the ground with wholesome
vegetation, and then the juices which would have otherwise fed
rankness will pour themselves into a more vigorous growth; the
dwindled weeds will be easily raked out then. It is an endless task to
be refuting error. Plant truth, and the error will pine away.

The instance to which all this is preliminary, is the pertinacious
hold which the belief in a human absolving power retains upon mankind.
There has perhaps never yet been known a religion without such a
belief. There is not a savage in the islands of the South Pacific who
does not believe that his priest can shield him from the consequences
of sin. There was not a people in antiquity who had not dispensers of
Divine favour. That same belief passed from Paganism into Romanism. It
was exposed at the period of the Reformation. A mighty reaction was
felt against it throughout Europe. Apparently the whole idea of human
priesthood was proved, once and for ever, to be baseless; human
mediation, in every possible form, was vehemently controverted; men
were referred back to God as the sole absolver.

Yet now again, three centuries after, the belief is still as strong as