Page:Popular Science Monthly Volume 27.djvu/175

Rh of the sensitive nerve-fibers. This is produced by the outward irritation, but is a purely physical and inward nervous process, having no other resemblance to its cause than that it is motion, and having no resemblance to the sensation which is conditioned upon it. 4. The transfer of this condition of the nerve-fiber to the central parts of the nervous system, especially to the brain. These are the mechanical antecedents for sensation. They are susceptible of physical treatment. They may, and often do, operate without any sensation arising; more than this, they may operate so as to produce a reflex activity, causing violent motions, still without the faintest appearance of sensation. It is plain, then, that to know anything about sensation we must pass from physiology to personal experience. It seems a just charge against the materialism of physiology, both general and medical, that it takes no account of the element in a sensation-process.

How shall we escape saying that the last step in this process is the sensation itself, which the soul calls forth from itself in consequence of the antecedents described? The sensation is no picture of the outer thing, the retinal image works, in all probability, chemically upon the retina, but that image does not and can not get itself transferred to the cerebral hemispheres. The sensation is an answer to the excitation in the brain-mass, arising from that image, an answer in such peculiar language that it must be called language of the soul—not as thereby explaining it in the sense of resolving its mystery, yet as thereby explaining it in the only way in which explanation is anywhere possible, viz., by resolving the combined activities into their elements.

It is a necessary part of this discussion to note that one of these elements is personality, i. e., a consciousness of the sensation as mine. It seems unfortunate that, in dealing with this experience of personality, the strength and weakness of the development theory are not rightly estimated. The strength of the theory lies in those rudimentary sensations connected with infant life, and with the organic processes where it seems but just to say that only feeling is present, i. e., no true consciousness, no knowledge of the sensation as mine. The weakness of the theory, and it is a fatal one, lies in the failure to recognize the distinction between a matured idea of self which comes only with years, and a consciousness that the sensation is mine, however rudimentary this sensation may be. The most primitive distinctions in consciousness, those of pleasure and pain, can not be experienced without being known. When this is realized, the inadequacy of the attempt to dispense with personality, or to derive it from anything more elementary than itself, must appear; the two factors in every phenomenon, viz., that which manifests itself, and that to which it manifests itself, are at once disclosed.

Memory, which, though lying in the so-called fog-land of consciousness, is yet a reality, has been brought forward as decisive against the application of evolution to the origin of knowledge. Memory is a