physical medium. The result followed as surely as the flash follows
when the electric battery and wire are both properly adjusted.
Corresponding experiments, where effect, and cause duly follow, are
being worked out at the present moment by Professor Crawford, of
Belfast, as detailed in his two recent books, where he shows that there
is an actual loss of weight of the medium in exact proportion to the
physical phenomenon produced.[1] The whole secret of mediumship on
this material side appears to lie in the power, quite independent of
oneself, of passively giving up some portion of one's bodily substance
for the use of outside influences. Why should some have this power and
some not? We do not know--nor do we know why one should have the ear
for music and another not. Each is born in us, and each has little
connection with our moral natures. At first it was only physical
mediumship which was known, and public attention centred upon moving
tables, automatic musical instruments, and other crude but obvious
examples of outside influence, which were unhappily very easily
imitated by rogues. Since then we have learned that there are many
forms of mediumship, so different from each other that an expert at one
may have no powers at all at the other. The automatic writer, the
clairvoyant, the crystal-seer, the trance speaker, the photographic
medium, the direct voice medium, and others, are all, when genuine, the
manifestations of one force, which runs through varied channels as it
did in the gifts ascribed to the disciples. The unhappy outburst of
roguery was helped, no doubt, by the need for darkness claimed by the
early experimenters--a claim which is by no means essential, since the
greatest of all mediums, D. D. Home, was able by the exceptional
strength of his powers to dispense with it. At the same time the fact
that darkness rather than light, and dryness rather than moisture, are
helpful to good results has been abundantly manifested, and points to
the physical laws which underlie the phenomena. The observation made
long afterwards that wireless telegraphy, another etheric force, acts
twice as well by night as by day, may, corroborate the general
conclusions of the early Spiritualists, while their assertion that the
least harmful light is red light has a suggestive analogy in the
experience of the photographer.

There is no space here for the history of the rise and development of
the movement. It provoked