conveyed through that medium. Destroy the
sight, and the mind can have no cognizance whatever of material objects
save through the sense of touch--for our knowledge of matter through the
senses of hearing, taste, and smell, is one of experience alone, which,
aided by sight and touch, has taught us in the past that where sound,
taste, or odor exist, there must be matter to produce these impressions.
Destroy, then, if it were possible, this sense of touch, and our
absolute perception of objects is entirely lost--the connection between
the outer world and the perceptive faculties of the mind is dissolved
forever. The truth of this position is seen in the fact that in a swoon,
when all the senses are benumbed, the mind is utterly unconscious of its
surroundings.

Again, to go to the other end of the chain--admitting that the force
which resides in the material points and produces the vibration in the
elastic medium is spiritual in its nature, do we not find that this
force never produces an impression upon the senses, and through them
upon the mind, except through the intermediate agency of a material
object? The object itself must exist before the force can act, and hence
arises our confidence in the evidence of our senses. Were it otherwise,
indeed, our whole life would be one of uncertainty, of innumerable
deceptions, a mere wandering about in a mist of delusions worse than
those of a maniac. And if this force could act upon our perceptions
without a material point in which to reside, is it not reasonable to
suppose that it would occasionally so do, and that we should sometimes
perceive effects for which we could find no cause in the material
world--no connection with matter? Yet in the whole range of human
experience no such thing is known. Even the phenomena which we call
optical illusions arise from certain derangements of the atomic
particles of the medium through which the impression is conveyed.

From this course of reasoning two plain deductions arise, either of
which is disastrous to the spiritualistic theory. For if we deny, as I
have done, that this hidden, mysterious force is spiritual in its
nature, we have in all our knowledge and experience no _instance_ of the
direct action of spirit upon matter. While, if we _acknowledge_ that
fact, we have still no instance of spirit so acting upon the medium
through which we receive our physical perceptions as to produce an
impression through the senses upon the mind,