Acuteness of perception, memory, logical thought, imagination, conception, emotional expression or inhibition and the entire content of consciousness are influenced by the internal secretions.  The most ultramicroscopic activities of the molecules and atoms in the highest nerve cells and nerve tissues are dominated.  The speed of their chemistry and their associations, and thus the speed of thought, are regulated.  Iodine has been shown to increase the electric conductivity of the brain that is, the rate at which electrons will fly through it.  The thyroid may then be regarded as manipulating the amount of iodine brought to play upon the brain cells at a particular moment of danger or exaltation.  Adrenalin increases the electric conductivity of the brain.  Nerve impulses, and with them sensations and ideas, travel faster or flow more quickly through iodinized or adrenalinized brain cells.  In dangerous situations we think more rapidly and keenly, for in emergencies the blood floods the brain with extra thyroid and adrenal secretions.

THE BODY-MIND COMPLEX

Mind, still regarded by most of mankind as something distinct and apart from the body, is thus exhibited as but part and parcel of it.  A deaf, dumb, and blind animal, deprived of tongue, and olfactory mucous membrane, without sensations from the outside world can grow no mind, in the sense of intelligence.  The sense organs of the body mediate the primary mind stuff.  Without internal secretions and a vegetative system there could be no soul, in the sense of complex emotion.  Nor those combinations of thought and emotion which synthesize attitudes, sentiments and character.  The internal secretions and the vegetative system mediate the primary soul stuff.  Mind is thus emulsified with body as a matter of cold literal fact.  The soul was once a subtlety of metaphysics.  Now when mind appears soaked in matter saturated with chemicals like the hormones, therefore woven out of material threads, the independent entity created out of intangible spirit flies like a ghost at dawn.

View the outlook.  Mind, the slippery phantom, now becomes controllable for the purposes of everyday life, because we can put our fingers upon, touch, handle and change these material factors, the internal secretions and the vegetative system.  Through them we may affect the very quality of the nerve tissue.  The future of the race, the future of human nature, depends upon the knowledge to be born of the researches into the vast possibilities of this idea.  Man, the Adventurer, the prey of Chance and Luck, will then become, indeed now becomes, the Captain of Fate and Destiny.

It is, of itself, a revolution in the intellect, to conceive of instincts and emotions, suggestibility and contra-suggestibility, initiative and imitation, volitions and inhibitions as chemical matters.  In all their relations, mutually reacting effects and defects, excesses and deficiencies, the internal secretions set up psychic echoes and reflections.  When morbid and their equilibrium dislocated, we may even have phobias and neuroses.