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, without the intervention of a material point. Is it reasonable, then, to suppose that in this our age, for the first time, a single solitary manifestation of this supernatural power should occur, as claimed by the spiritualists, unaccompanied by any analogous contemporary or corroborative fact of the same or of a different nature? To admit this is to admit one of three things: 1st, that both the physical senses and spiritual constitution of humanity have undergone a sudden and wonderful change; 2dly, that the Almighty has entirely altered his mode of communication with mankind; or, 3dly, that the whole world of spirits has been let loose to wander at will over the universe and space!