based on pure physical evidence,
and not on any inherent, unreasonableness in the act of prayer. The
theory that the system of nature is under the control of a Being who
changes phenomena in compliance with the prayers of men, is, in my
opinion, a perfectly legitimate one. It may of course be rendered
futile by being associated `with conceptions which contradict it; but
such conceptions form no necessary part of the theory. It is a matter
of experience that an earthly father, who is at the same time both
wise and tender, listens to the requests of his children, and, if they
do not ask amiss, takes pleasure in granting their requests. We know
also that this compliance extends to the alteration, within certain
limits, of the current of events on earth. With this suggestion
offered by experience, it is no departure from scientific method to
place behind natural phenomena a Universal Father, who, in answer to
the prayers of His children, alters the currents of those phenomena.
Thus far Theology and Science go hand in hand. The conception of an
aether, for example, trembling with the waves of light, is suggested
by the ordinary phenomena of wave-motion in water and in air; and in
like manner the conception of personal volition in nature is suggested
by the ordinary action of man upon earth. I therefore urge no
_impossibilities_, though I am constantly charged with doing so. I do
not even urge inconsistency, but, on the contrary, frankly admit that
the theologian has as good a right to place his conception at the root
of phenomena as I have to place mine.

But without _verification_ a theoretic conception is a mere figment of
the intellect, and I am sorry to find us parting company at this
point. The region of theory, both in science and theology, lies
behind the world of the senses, but the verification of theory occurs
in the sensible world. To check the theory we have simply to compare
the deductions from it with the facts of observation. If the
deductions be in accordance with the facts, we accept the theory: if
in opposition, the theory is given up. A single experiment is
frequently devised, by which the theory must stand or fall. Of this
character was the determination of the velocity of light in liquids,
as a crucial test of the Emission Theory. According to it, light
travelled faster in water than in air; according to the Undulatory
Theory, it travelled faster in air than in water. An experiment
sugges