ays: "In all that I had witnessed, and indeed in all the
wonders which the amateurs of mystery in our age record as facts, a
material human agency is always required. On the Continent you will
still find magicians who assert that they can raise spirits. Assume for
a moment that they assert truly, still the living, material form of the
magician is present, and he is the material agency by which, from some
constitutional peculiarities, certain strange phenomena are represented
to your natural senses.... Accept again as truthful the tales of spirit
manifestation in America, produced by no discernible hand--articles of
furniture moved about without visible human agency--or the actual sight
and touch of hands to which no bodies seem to belong--still there must
be found the "medium," or living being, with constitutional
peculiarities capable of obtaining these signs. In fine, in all such
marvels, supposing even that there is no imposture, there must be a
human being like ourselves, by whom, or through whom, the effects
presented to human beings are produced."

[10] It should be said, however, that--apart from its innate
difficulties--this theory has recently received its death-blow by the
discovery of the fact that space is filled with ultra-violet rays, which
would soon prove fatal to all forms of life.

[11] See, especially, Duncan, _Some Chemical Problems of Today_, pp.
63-83 and 97-104.

[12] "Rector" is the name of Mrs. Piper's chief control and amanuensis,
during her trance sittings.

CHAPTER II

INVESTIGATING PSYCHICAL PHENOMENA WITH SCIENTIFIC INSTRUMENTS

It is generally conceded that Aristotle possessed the greatest single
intellect the world has ever known; yet any schoolboy today knows more
of the structure of our universe than did Aristotle! The reason for this
is that Science has more fully penetrated the secrets of Nature, and we
now know approximately the constitution of matter and a good deal
concerning life and mind. How has this progress been possible? Only in
one way. Improvement in the _mechanical instruments_ by means of which
we study Nature. We might "speculate" as to the constitution of matter
for a thousand years, but we should never have arrived at our present
positive _knowledge_ had it not been for the delicate and sensitive
instruments which are today in the hands of the physicist and the
chemist, and employed by him in his laboratory.

Doubtless much the same law will be found to