Page:Popular Science Monthly Volume 15.djvu/104

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94
THE POPULAR SCIENCE MONTHLY.

in the sensiferous apparatus are continuous with, and similar to, those which take place in the external world.[1] But, with the sensorium, matter and motion come to an end; while phenomena of another order, or immaterial states of consciousness, make their appearance. How is the relation between the material and the immaterial phenomena to be conceived? This is the metaphysical problem of problems, and the solutions which have been suggested have been made the corner-stones of systems of philosophy. Three mutually irreconcilable readings of the riddle have been offered.

The first is, that an immaterial substance of mind exists; and that it is affected by the mode of motion of the sensorium in such a way as to give rise to the sensation.

The second is, that the sensation is a direct effect of the mode of motion of the sensorium, brought about without the intervention of any substance of mind.

The third is, that the sensation is neither directly, nor indirectly, an effect of the mode of motion of the sensorium, but that it has an independent cause. Properly speaking, therefore, it is not an effect of the motion of the sensorium, but a concomitant of it.

As none of these hypotheses is capable of even an approximation to demonstration, it is almost needless to remark that they have been severally held with tenacity and advocated with passion. I do not think it can be said of any of the three that it is inconceivable, or that it can be assumed on a priori grounds to be impossible.

Consider the first, for example; an immaterial substance is perfectly conceivable. In fact, it is obvious that, if we possessed no sensations

  1. The following diagrammatic scheme may help to elucidate the theory of sensation:
    Mediate Knowledge
    Immediate
    Sensiferous Apparatus Knowledge
    Objects of Sense Receptive Transmissive Sensificatory Sensations and
    (Sense-Organ) (Nerve) (Sensorium) other States of
    Consciousness
    Hypothetical Hypothetical
    Substance of Substance of
    Matter Mind
    Physical World Mental World
    Not Self Self
    Non-Ego or Object. Ego or Subject

    Immediate Knowledge is confined to states of consciousness, or, in other words, to the phenomena of mind. Knowledge of the physical world, or of one's own body and of objects external to it, is a system of beliefs or judgments based on the sensations. The term "self" is applied not only to the series of mental phenomena which constitute the ego, but to the fragment of the physical world which is their constant concomitant. The corporeal self, therefore, is part of the non-ego; and is objective in relation to the ego as subject.