Man’s nerve cell organization may be classified into two main systems:

(I) The inferior, the reflex, the instinctive, the automatic centers.

(II) The superior, the controlling, selective, and inhibitory brain-centers of the cortex.

The double systems of nerve-centers have correspondingly a double mental activity, or double-consciousness as it is sometimes called, the inferior, the organic, the instinctive, the automatic, the reflex consciousness, or briefly termed the subconsciousness, consciousness below the threshold of self-consciousness; and the superior, the choosing, the willing, the critical, the will-consciousness. This controlling will-consciousness may also be characterized as the guardian-consciousness of the individual.

From an evolutionary standpoint, we can well realize the biological function or importance of this guardian-consciousness. The external world bombards the living organism with innumerable stimuli.[78] From all sides thousands of impressions come crowding upon the senses of the individual. Each neuron system with its appropriate receptors has its corresponding system of reactions which, if not modified or counteracted, may end in some harmful or fatal result.

It is not of advantage to an individual of a complex organization to respond with reaction to all impressions coming from the external environment. Hence, that organism will succeed best in the struggle for existence that possesses some selective, critical, inhibitory “choice and will” centers. The more organized and the more sensitive and delicate those centers are, the better will the organism succeed in its life existence.

The guardian-consciousness wards off, so far as it is possible, the harmful blows given by the stimuli of the external environment. In man, this same guardian consciousness keeps on constructing, by a series of elimination and selection, a new environment, individual and social, which leads to an ever higher and more perfect development and realization of the inner powers of individuality and personality.

Under normal conditions man’s superior and inferior centers with their corresponding upper, critical, controlling consciousness together with the inferior automatic, reflex centers and their concomitant subconscious consciousness, keep on functioning in full harmony. The upper and lower consciousness[............