This section is from the book "Handbook Of Suggestive Therapeutics, Applied Hypnotism, Psychic Science", by Henry S. Munro. Also available from Amazon: Handbook of Suggestive Therapeutics, Applied Hypnotism, Psychic Science.
Most certainly "psychical" and "conscious" are primarily identical, but the changes wrought upon the neuron elements as the result of all experience may functionate again and again, though the individual may be consciously unaware of such effects, and these are very aptly designated as "subconscious psychical processes." They are the physiological residue of passing mental states that are retained by the neuron elements, and functionate as often in the life of the individual as they are aroused by similar experiences. They are brought to life, as it were, through the association of ideas.
1 Theodor Ziehen: Physiological Psychology.
All of our experiences - everything that we have thought, seen, heard, or felt - are conserved in such a way that they can be reproduced in a form approaching that of the original experience. Memory is but the impress conserved by our brain cells and reproduced by ideas suggesting the original experience.
"Through the sensory nerves the brain receives, through the motor nerves the brain directs, and this whole arch from the sense organs through the sensory nerves, through the brain, through the motor nerves and finally to the muscles, is one unified apparatus of which no part can be left out. The necessary relation between the sensory and motor parts should ever be kept in mind, for there can be no sensory process which does not go over into motor response. The whole mental life thus becomes the accompaniment of a steady process of transmitting impressions and memories into reactions." 1 Munsterberg has well said that suggestions which are not suggestions of actions are, without exception, suggestions of belief. Actions and beliefs are the only possible material of any suggestion - the tool of psychotherapy. Psychotherapy simply makes employment of the normal mechanism of the mind and body - of the physiological machinery already provided. By the employment of suggestion we bring about a restitution of the disordered functions.
Suggestion can act only as a therapeutic agent by stimulating the physiological mechanism; it can not create anything new, or do anything that is not in accord with the laws of the nervous system.
The first beginnings of a nervous process are to be found where animal anatomy first meets with a nervous apparatus in the ascending scale of animal life. A certain capacity for nervous processes are recognizable in the motor activity of even the simplest ameba. We can imagine a monad to be placed before us and a grain of sand to be brought in contact with it. Protoplasmic masses, the so-called pseudopodia, stretch themselves out, envelop the grain, and incorporate it within the body of the main mass. In this process there are exhibited those features which we recognize as the essentials of nervous function - viz., (1) a sensible stimulation, and (2) a reaction; in fact, a motor effect that is by no means explicable to merely physical laws. Hence, wherever we find contractile substance, the conditions of nerve life are al-ready present.1
1 Hugo Munsterberg.
This is true though only one cell be the seat of the reception of the stimulus and the motor reaction. In this way the development of the nervous system begins, the gradual accomplishment of which - in the jellyfish, for instance - might be conceived as follows: Here is an animal composed of many cells, and any given stimulus with which it is brought in contact is constantly transmitted as an excitation within the animal along the path offering the least resistance. Thus the excitations will come to be transmitted only along fixed paths, the so-called paths of conduction. According to a fundamental law of biology, the constant execution of definite functions also gradually effects certain structural modifications. Accordingly these paths of conduction become anatomically differentiated from their surroundings, and the nerves develop into independent anatomical tissues. Next is developed the so-called ganglion cell, a mediating organ between the sensory conductor receiving the stimulation and the motor conductor imparting contraction. When the stimulus acting upon the nerve end reaches a ganglion cell, and is transmitted by the latter along a new nerve path to contractile masses, so as to impart motion, the entire process is designated as reflex action.
Reflex action is the simplest nervous process of which we have any knowledge. By reflex action in higher animals we understand a motion imparted by a stimulus upon a sensitive periphery. A prick of the sole of the foot is answered by a withdrawal of the foot by flexion and, to some extent, by contraction of the toes. In this case the essential anatomical elements of the process are thoroughly known. In the sole of the foot are the terminations of sensory nerves. These are irritated, and conduct the stimulus, or excitation, to a sensory ganglion cell in the spinal cord. This cell sends the excitation received along to the motor ganglion cells, which in turn transmit the impulse again toward the periphery and generate muscular activity.
1 Theodor Ziehen: Introduction to the Study of Physiological Psychology, page 6.
Whether a concomitant psychical process corresponds to the nervous process concerned in reflex acts, our consciousness alone is able to decide. However this may be, the biological elements concerned in the process possess and exercise their own psychic potentialities, whether recognized by our consciousness or not, and those psychical processes which correspond to physiological functions of which we are consciously unaware may very appropriately be designated as subconscious psychical or mental processes, which have their own physical correlative. Hence, the employment of the terms "conscious" and "subconscious" as applying to the organized physiological processes of the higher and lower neuron systems respectively, whether accompanied by consciousness or unconsciousness, or controlled by volition or automatic function.