The subject of fear may be considered from a somewhat different point of view, namely from a purely physiological and biological aspect. The cell in general, the nerve cell, or neuron, is a reservoir of energy. In fact the great biologist Sachs proposed to term the cell, energid.

For we must look at the organism as a store of energy which is used up in the course of the adjustments of the individual to his environment. The organism stores up energy and uses the energy during the course of its life activity.

Life energy is physiological, bio-chemical, electrical, mechanical, etc. The mental and emotional activities are intimately related with the expenditure of energy accumulated by the cells of the organism, which discharge that energy in response to the various stimulations of the external world. In its activities the organism keeps on taking in energy, and once more discharging energy in its life reactions. The storing up of energy falls under the anabolic or building up processes, while the discharging[333] or liberating processes of the amount of the stored up energy are classed under the katabolic processes.

The total cycle of energy from the start of storage to the end of liberation of energy, starting once more with the storing of energy, may be regarded as the cycles of organic functional activity which is classified under metabolism. We deal here with a reservoir of vital energy whose life activities or reactions depend on the amount of energy contained in the cell or the neuron, and whose functioning and reactions vary with the level of energy in the reservoir.

The neuron is but a highly differentiated cell or reservoir for the intake and outgo of energy. In this respect the nerve cell is entirely like other cells of humbler function. Every cell is a storage cell, accumulating energy and then liberating it at an appropriate occasion of a given stimulus, all cells working for the preservation of the organism as a whole. The rise and fall of the level of energy in the reservoir regulate the various manifestations, sensory, motor, emotional, mental which the individual displays to the various stimulations coming from his environment.

Within certain limits the fall of energy is normal,—when it reaches a certain level the organism once more replenishes the store and once more the level of energy rises. This energy is Dynamic under certain[334] conditions. However, the discharge of energy must go on, and the organism must draw further on its store of energy, on the accumulated store of energy put away for safety and emergency. This stored up energy is Reserve Energy.[16]

The late Charles S. Minot, the American histologist, points out this reserve energy present in the organism, a reserve energy of growth called forth under special emergencies of life.

By a striking series of instructive facts, Dr. Meltzer points out that “all organs of the body are built on the plan of superabundance of structure and energy.” Like Minot, Meltzer refers to the significant fact that most of our active organs possess a great surplus of functioning cells. This surplus is requisite for the safety of the individual.

If, however, the drain of energy still goes on without replenishing the total store, the energy drawn on the region of the danger zone is entered. This energy is Static. The concomitant symptoms are various psychomotor and psycho-secretory disturbances of a psychopathic or psycho-neurotic character. This energy is drawn from the upper levels of energy. Under such conditions restitution of the total amount of energy to its normal level is still possible.

Should the process of liberation of energy go on[335] further without restitution, the energy drawn is taken from the lower levels of static energy, and the symptoms are functional, neuropathic. The lower-most levels of static energy are t............