The nervous system and its nerves have long been a mystery.  Being similar in appearance to veins or sinews, nerves were often confused with these structures.  But it soon became apparent that nerves carried consciousness (sensory) and volition (motor).
     In Homer's time, consciousness was thought to reside in the heart, but by Hippocrates' day, the brain, or encephalon was recognized as being its seat.  Galen established that the root and origin of the nerves was in the brain.  From the brain, the spinal cord extends downwards into the body as the nervous system's central trunk, or nexus, from whence branch out the spinal nerves, like an inverted tree, to innervate every part of the body.
     By severing various spinal nerves in apes and other test animals, Galen mapped out the dermatomes, or regions of the body innervated by each spinal nerve.  Avicenna describes the various nerves of the body at length in his Canon of Medicine.  In his day, only seven cranial nerves had been discovered.
     The nerves were seen to be of a single, homogeneous tissue type, essentially made up of the same stuff as bone marrow and resembling it in general texture and appearance.  Like the marrow, they were also seen to originate inside the bones - the cranium and spinal vertebrae.  Being cold, dry and Melancholic in temperament, it was recognized that the nervous tissue, like the bones, grew and regenerated very slowly, if at all.  Being Melancholic in temperament like the bones, the nerves are also vulnerable to Melancholic or nervous pathologies: nervous, aesthenic or spasmodic afflictions, and neuromuscular disorders. 
     The nerves were seen to carry the Psychic Force, also called the Animal Spirits, or simply Spiritus - an energy so ethereal and refined as to be the very essence of consciousness itself.  To conduct Spiritus with such lightning-like speed, the nerves were long thought to be hollow, like the arteries or veins.  It was a long time before scientific research finally dispelled the notion. 
     The functioning of the nervous system and the flow of its Spiritus was magical and mysterious.  Likewise, the various abberations of consciousness and dysfunctions of the nervous system were equally mysterious and difficult problems to solve. 
     Quite early on, powerful medicines, usually of botanical origin, were discovered which had a profound effect on the Psychic Faculty and nervous system.  Tincture of Belladonna, applied topically, could dilate the pupils of the eyes.  Mistletoe was a powerful antispasmodic and anticonvulsant that could treat and prevent epileptic seizures.  Henbane had powerful antispasmodic effects on the muscles and bowels.  The powerful effects of these medicines couldn't be explained by the usual laws of taste and temperament alone, as they seemed to have a magical special potency.
     Perhaps the most famous of these wonder drugs was Opium, or Papaver somniferum, the sleep inducing poppy.  Even though it was a powerful painkiller, Galen was fully aware of its addictive nature, and considered it, at best, to be a mixed blessing.
     Because of the powerful nature of these drugs, overdosing can be fatal; therefore, they should only be used under professional supervision.

The Brain

     The head leads, and the body follows.  And inside the head as its kernel or nucleus lies the brain, or Enkephalos in Greek.  The head and its brain, being at the top of the body and nearest to heaven, are the organs of the Soul, or psyche.  The brain is the principal organ of the Psychic Faculty, and all the various nerves and organs of this faculty, which is basically the nervous system, exist to serve it.
     The brain is a temperate organ, being only slightly cold.  Therefore, it is equally vulnerable to excessive heat and fevers as it is to cold and chills.  Heat aggravates and excites the mental functions, causing agitation and delirium, whereas cold depresses the mental functions, causing sluggishness and lethargy.
     The brain is moderately moist by nature, making it a Phlegmatic organ.  Although excessive phlegm and dampness can oppress the brain and mental functions, by far the greater danger is from dryness and dehydration.  The inherent wetness of the brain is, according to Greek Medicine, the source of its great sensitivity and powers of perception.
     The watery, Phlegmatic nature of the brain is further enhanced by the fluid-filled ventricles which permeate it, and by the meninges which encase it.  In traditional Greek Medicine, the ventricles of the brain serve as channels or passageways for the flow of its Psychic Force, or consciousness.  Loss of consciousness occurs when these passageways are blocked or obstructed. 
     Because of its Phlegmatic nature and temperament, the brain gives off various watery, Phlegmatic distillations and exudations from time to time, according to Greek Medicine.  These include a runny nose, nasal and sinus congestion, and post-nasal drip.  These conditions can create inflammatory congestions called catarrhs, which literally means, "flowing down".
     The sensory nerves are receptive, afferent attendant vessels of the brain, which receive sensory data and impressions.  The motor nerves are emissive efferent attendant vessels of the brain, which execute responses to stimuli.
     Although the sensory functions of the brain are served primarily by the sense organs of sight, touch, taste, smell and hearing, the brain, being the most Phlegmatic and sensitive by nature, is the ultimate sense organ.  According to its nature, it will spontaneously delight in certain sensations and be revolted by others.  The Faculty of Common Sense in the brain pieces together a composite picture or facsimile of the outer world from information fed to it by the sense organs, which it uses to cognate and act.
     The Alexandrian anatomists Herophilus and Erasistratus, through their dissections, made great discoveries about the brain and how it worked.  They mapped out its basic parts and structure, its ventricles, and the like.  They postulated that man's superior intelligence came from the greater number of folds or sulci in his cerebral cortex.  They also established that the left side of the brain controls the right side of the body, and vice-versa.  Galen advanced the understanding of mental disorders, and was a pioneer in this field.


Relationships of the Brain to Other Organs

     The brain, through the nervous system, is related to every other organ, tissue and part of the body.  Although early physiologists like Galen could vaguely intuit the profoundness and pervasiveness of this inter-relationship, it was left to modern medicine to thoroughly map out its full extent.
     Most proximally, the brain, seated in the center of the cranial cavity, governs the head and its sensory organs and orifices: the eyes, ears, nose, mouth and tongue.  By examining the condition of these sensory orifices, the astute physician can tell a lot about the brain, since conditions of humor and temperament affecting the former often affect the latter.  Nerves go directly from these sense organs to the brain.
     The Psychic and Vital faculties are connected via the mutual feedback loop between head and heart, described in the Psychic Faculty page under Basic Principles.  In return, the heart and its peripheral circulation vitalize the brain by pumping pneuma rich blood up to it.  Pumping fresh blood all the way up to the brain requires good vigor and robustness of the heart.  Of all the organs, the brain is one of the greatest consumers of oxygen/pneuma, and poor cranial blood supply is a major cause of brain fatigue.
     The brain and heart are also partners in the maintenance of consciousness, according to Greek Medicine.  The heart is the seat of the emotional or Vital mind.  Like the brain's ventricles, the heart also has subtle passageways that are channels for the flow of spirit and consciousness.  Loss of consciousness can occur when the harmonious flow and communication of spirit or consciousness between the brain and heart, assisted by the lungs, is obstructed or disrupted.
     Supporting the heart and strengthening the vigor of its contractions are the adrenal glands.  Having a good peripheral and cranial circulation depends, to a large measure, on the strength of the adrenals.  The adrenals also support the sympathetic nervous system, which heightens mental alertness.  Adrenal exhaustion is a major underlying cause of brain fatigue.
     The soundness of the brain and the strength and clarity of its mental functions also depend in large measure on a sound, balanced stomach and digestion.  A stomach plagued by indigestion and a disharmony of its humors will similarly weaken, unbalance, agitate and disturb the mind.
     Underlying and supporting the stomach and its functioning is the colon, or large intestine.  and the intestines in general.  If the intestines are a cesspool, a condition known as alimentary toxemia, the mind and its thoughts and overall disposition will be similarly morbid and disturbed.
     And, when all else fails, don't forget to breathe!  Healthy, optimal respiration underlies all healthy brain function, since the lungs are the source of all pneuma in the body.  Yogis and spiritual adepts use special breathing exercises to heighten and expand their mental and spiritual powers.

The Nervous System

     Extending downwards and outwards from the brain, the nerves that serve it are basically of two types:
     Afferent sensory nerves, whose greater sensitivity and receptivity come from being softer and moister in temperament;
     Efferent motor nerves, whose active, emissive nature and function come from being harder and dryer in temperament.
     Most of the sensory nerves, especially those going to the sense organs, lie quite close to the brain itself, and extend directly from it.  The main exception is the sense of touch, which pervades throughout the whole body.
     The brain and spinal cord constitute the central nervous system; encased in fluid-filled meninges, its nature is softer, moister, and more sensitive, subjective and Phlegmatic.  The nerves of the peripheral nervous system, which branch out from the spinal cord, are harder, dryer, and more active and objective.
     The nervous system can be further subdivided into conscious or voluntary versus autonomic, or the automatic, involuntary functions lying below the threshold of consciousness.  Early physiologists like Galen knew something of the autonomic nervous system and its functioning: Galen discovered its Sympathetic branch, and so named it because he felt that it conveyed the sympathies, as when the heart jumps for joy.
     However, it was left to modern medicine to thoroughly discover and map out the full extent of autonomic nervous control over key bodily functions like digestion, respiration, heartbeat and circulation.  Traditional Greek physicians had previously attributed them to the direct action of pneuma and other vital principles, as well as the Four Humors and their respective Administering Virtues.
     The autonomic nervous system is divided into two complementary halves:  Sympathetic and Parasympathetic.  It is in balancing these two Yang and Yin halves of the autonomic nervous system that herbal medicine and other holistic healing modalities have their greatest value.
     The Sympathetic nervous system is the Yang half of the autonomic nervous system, and mobilizes the body for action.  It is centered in the Sympathetic chain ganglia that line both sides of the spinal column, and is closely connected with the adrenaline "fight-fright-flight" response.  Under Sympathetic influence, the heart beats faster and harder, the respiratory rate increases, the blood vessels constrict and blood is shunted outwards towards the muscles, extremities and periphery.  Muscle tone tightens, and mental alertness increases.
     The Parasympathetic nervous system supports and promotes the anabolic and vegetative functions of the organism, which favor rest, relaxation and regeneration.  It is divided into two halves, and is the Yin complement of the Sympathetic.
     The Vago-parasympathetic nervous system prepares the body to relax and receive.  It has a restorative effect on the heart and vascular system, and stimulates the vegetative and assimilative functioning of the digestive organs.  It is centered in the Vagus nerve, which descends from the brain through the throat and down into the chest and abdomen. 
     The Sacro-parasympathetic branch prepares the body to relax and release, and governs the eliminative functions: urination, defecation, ejaculation and childbirth.  It is centered in the Sacral nervous plexus.
     The moist Phlegmatic and Sanguine temperaments favor the Parasympathetic branch, whose restorative and anabolic functions depend on and favor a bountiful supply of the Radical Moisture.  The Phlegmatic temperament favors an excess or preponderance of the Parasympathetic function, whereas the Sanguine is more balanced.
     The dry Choleric and Melancholic temperaments favor the Sympathetic branch.  In Cholerics, the Sympathetic hyperstimulation tends to be more acute and vehement, whereas in Melancholics it's more chronic and aesthenic, associated with neuraesthenia and a deficiency of the Radical Moisture.
     In today's stress-ridden world, hyperstimulation or aggravation of the Sympathetic nervous system to the detriment of the Parasympathetic is by far the greater problem.  It is behind many of the chronic degenerative diseases seen today: heart disease, insomnia, palpitations, high blood pressure, ulcers, colitis, gastritis, indigestion, adrenal exhaustion and so on.  This Sympathetic dominant imbalance is most commonly seen in two forms:
     Neuraesthenia is a generalized exhaustion and wasting away of the nerves, and is associated with nervousness, palpitations, insomnia, tremors tics and spasms, neuralgias and the like.  Sympathetic hyperactivity depletes the Radical Moisture and nutritive integrity of the nervous system and its nerves.
     Neurovegetative dystonia pertains mainly to the digestive organs and a compromising of their blood supply and vegetative functioning, and underlies many of the common nervous, colicky, spasmodic, irritable or ulcerous digestive complaints.  It often starts with eating while tired, stressed, emotionally upset or on the run.
     In managing and balancing these two complementary halves of the autonomic nervous system, diet, nutrition and medication alone are not enough.  Management of lifestyle factors and living habits like activity and rest, sleep and wakefulness, and perturbations of the mind and emotions is also important.


Conditions of the Brain and Nervous System

     The brain, and hence the whole nervous system, can be influenced by the morbid vapors of excessive or aggravated humors, which lead to various syndromes of disharmony or dysfunction.   Each of the Four Temperaments is most prone to aggravations of its corresponding humor.  These humoral syndromes produce both psychic and physical manifestations, as follows:
     Phlegmatic:  Sluggishness, torpor, passivity, and somnolence prevail.  Senses dull, mental alertness falters, reflexes slow.  Drowsiness, somnolence especially problematic in early mornings, after meals, in evenings after a hard day's work.  Head often heavy, with a sense of pressure as if a thong were wrapped around it, is quite common.  Nose and sinuses often watery and congested, eyes can water or tear easily, ears can easily get congested or stopped; can also be excessive salivation.  In severe cases, dizziness and vertigo, faintness, wooziness, or even syncope or loss of consciousness can occur.
     Sanguine:  Excess blood can also produce drowsiness, lethargy, due to moisture of Sanguine humor.  May also be frequent yawning, a feeling of pressure behind the eyes, headache.  Excess blood can also be let off as nose bleeds, although this can also be caused by excess heat and choler in the blood.  The eyes can develop problems like swelling, conjunctivitis.  Mind often given over to sensuality, idle pleasures and distractions.  Sanguine conditions like high blood pressure can predispose one to various cranial disorders, like apoplexy, aneurysms, stroke and cerebrovascular accidents.
     Choleric:  Hot, choleric vapors can rise from the liver to disturb the head and brain.  Signs and symptoms: tension in neck and shoulders, vehement headaches or migraines, nosebleeds, visual disturbances and photophobia, red sore bloodshot eyes, vertigo, ringing in the ears.  The mind will be angry, irritable, moody or impatient.  The face will often be bright red.  Severe aggravations of heat and choler, often associated with the delirium of a high fever, can provoke giddiness, nausea and even dry heaves.  This condition can often generate internal wind, causing mania, deviation of the eyes mouth and tongue, apoplexy, convulsions and syncope. 
     Melancholic:  The syndromes and disorders associated with the Melancholic disposition are many and varied; the Melancholic temperament is often called the Nervous temperament.  They include the following:
     Neuraesthenia:  Weak, frayed nerves; an exhausted brain and nervous system.  Excessive thinking and worrying drains valuable minerals, electrolytes and Radical Moisture from the brain and nervous system.  Signs and symptoms: nervous agitation, hyper-reactivity; being easily startled; chronic stress, insomnia; tremors, tics, spasms and neuralgias; dizziness, tinnitus, vertigo; a thin, furtive sweat that's aggravated by nervousness.
     Neurovegetative dystonia:  A hyperstimulation of the Sympathetic nervous system to the detriment of the Parasympathetic digestive and vegetative functioning.  Signs and symptoms: poor appetite, chronic indigestion; various nervous, irritable, spasmodic or colicky digestive disorders of the Melancholic type.
     Cerebrovascular disorders:  Infarction or poor blood circulation and oxygen/pneuma supply to the brain.  Clots and embolisms, causing cerebrovascular accidents.  Hardening and stenosis (narrowing) of the cerebral arteries and blood vessels, increasing the risk of embolism or hemorrhage.  Poor cerebral blood supply, since the Melancholic temperament is contrary to the Sanguine.
     Fainting, syncope, loss of consciousness:  Usually preceded by a feeling of dizziness, lightheadedness due to Melancholic dryness.   This is contrary to the wet heaviness of the head experienced in the Phlegmatic and Sanguine types.
     Melancholic cranial syndrome:  Similar in many ways to the Choleric type, but not as hot, acute or vehement.  Headaches, migraines are chronic and recurring, but pain, giddiness and nausea aren't as intense; instead of photophobia, visual floaters are more common.  Eyes, instead of being red and sore, are only dry, irritated or scratchy.  Instead of acute spasms and convulsions, chronic or recurring tremors, tics or spasms.  Dizziness, tinnitus or vertigo may be present, but not as acute or vehement.
     Mental outlook:  Pensive, moody, morose - contrary to robust wellbeing of the Sanguine.  A vague feeling of malaise and "hypochondria" - pain, fullness and distension under lower ribs, which can constrict chest and breathing, and disturb stomach and digestion.  This is due to the accumulation of excess black bile in the liver and underneath the lower ribs. 
     Such are the basic conditions of the brain, mind and nervous system associated with the Four Humors and their respective temperaments. But morbid humors can combine to create other signs, symptoms and syndromes.  For example, wind stemming from the Nervous humor can team up with phlegm to create a very fine phlegm that can mist or block the sense organs and their orifices, creating hallucinations, visual or sensory obscurations and disturbances, convulsions, fainting or syncope.  


The Mind and Its Disorders

     The brain is the physical organ of the supra-physical mind, which is the subtle vehicle for the indwelling Soul.  All consciousness and volition reside ultimately in the Soul.  In its dealings with the phenomenal universe and the physical world, the Soul uses the subtle mind, which in turn uses the physical brain and nervous system.
     The brain and mind work through several different faculties, which I have described in the page on the Psychic Faculty in the Basic Principles section.  These faculties fall into three different categories:
     Sensory:  sight, hearing, smell, taste and touch; the Faculty of Common Sense.
     Intellective:  Ideation, Judgement, Memory, Empathy
     Motor:  the motor nerves and their muscles and effector organs
     According to Medical Astrology, the mind functions at three different levels, each of which could be called a different faculty, or mind:
     The Mundane Mind, symbolized by Mercury in the natal horoscope.  The lowest level of mind, incorporating the Faculty of Common Sense.  A big sensorimotor computer, collecting sensory data, processing and tabulating it, and responding to it, mainly through conceptualization, intellect, speech, communication, manipulation, digital dexterity.  Through practice and memorization, the Mundane Mind masters basic skills and competencies, which is its greatest strength.
     The Mundane Mind doesn't perceive outer reality directly, but rather through the medium of the five senses.  The Faculty of Common Sense puts together an inner mental facsimile or composite picture of the outer world by piecing together incoming sensory data in the right way. 
     Mental health results when the Mundane Mind's inner facsimile of the outer world is clear, orderly and accurate, and when the mind is able to distinguish clearly between its own creations and outer reality.  Mental illness results when these facsimiles become garbled, confused and unclear, or when the inner world of imagination or fantasy intrudes on the outer world.
     The Mundane Mind is basically amoral; technical facility, or how to do things, is its only concern.  Mercury is the god of thieves, con-men and tricksters.  The Mundane Mind is easily influenced by its associates and surroundings, for good or ill.  This lower mind is a great servant but a bad master, and needs guidance from the higher levels of mind and Soul.
     The Higher Mind or Philosophical Mind is symbolized by Jupiter in the natal horoscope as the guru, guide or wayshower.  Its chief concern is philosophy, morals and ethics, in following that which is right and true towards the path of one's Highest Good.  The Mundane Mind asks only if something can be done, and how; whether or not something should be done, and why, is the concern of the Higher or Philosophical Mind, which speaks to us through our conscience. 
     Modern man faces many moral and ethical dilemmas that are clearly posing a great challenge to his Philosophical Mind..  Clearly, modern technology has run amok, and not everything that can be done should be done.  Sophisticated high technologies come easily, and are a dime a dozen compared to the moral and ethical development and maturity necessary to apply them in an appropriate, constructive manner for the greater good of mankind.
     The Spiritual Mind is that which is closest to Soul in its nature.  It sees the grand panorama of life and destiny, the whole picture, and knows things by direct perception.  Information comes to it in sudden flashes of cognition or insight.  Its essence transcends logic, and could be called intuitive, or noetic.  The Spiritual Mind is the source of all true genius and revelation, and is symbolized by Uranus in the natal horoscope.
     In the vast majority of mankind, the Spiritual Mind is relatively latent, subliminal and undeveloped.  This is actually a blessing, because many individuals don't  have the necessary development and strength of the other mental levels to withstand the power of the Spiritual Mind which, if unchecked, can easily unground and overwhelm, creating spiritual disorientation and vertigo.
     As unique individuals, we all have our own particular strengths and weaknesses, gifts and impediments when it comes to these three levels of mind.  Mental health and wellbeing come when all three levels of mind are working together in a harmonious, balanced fashion; mental disorders come when this harmonious working relationship is disturbed.  The Mundane Mind will experience confusion, delusion or incompetency; the Philosophical Mind will suffer moral or ethical misgivings, or crises of conscience or purpose; and the Spiritual Mind can get ungrounded or unbalanced, and upset or overwhelm the lower levels.
     Many mental and emotional disorders have their origin in overwhelming, traumatic experiences that the mind and its faculties are unable to process or digest properly.  These could be called disorders of psychic pepsis.  The mind gets stuck in psychic indigestion and is unable to move on until these traumatic experiences are properly processed or resolved.
     According to their individual constitutional makeup, each person will experience mental disorders or imbalance in their own particular way.  The typical parameters for the Four Temperaments are as follows:
     Choleric:  Mania, delirium; mental agitation and an inability to attain mental peace and composure.  Irascibility, irritability, negativism, hypercriticalness.  Violent or abusive tendencies.  Hyperactivity.   A bombastic hyperemissiveness, unable to be receptive and a good listener.  Fanaticism, extremism, paranoia.
     Sanguine:  Excessive joy and euphoria.  A blind, mindless addiction to the pleasure principle.  Inability to withstand hardship, deprivation, delayed gratification.  Inability to give prolonged attention and concentration to the serious concerns of life.  An endless search for distractions.  Self gratification at the expense of others.
     Melancholic:  Excessive isolation and withdrawal.  An excessively cautious, prudent outlook; getting too easily fearful, circumspect or discouraged.  Passive, reclusive paranoia.  Obsessive, rigid or dogmatic thinking.  Easily startled or frightened.  Self-alienation, denial of one's feelings.  Depression, hypochondria, malaise.  Hoarding, miserliness, misanthropy, suspicion; inability to trust others.
     Phlegmatic:  Mental torpor, passivity, sluggishness, depression.  Unrealistic, passive fantasies, illusions, delusions.  Hyper-receptivity, hypersensitivity, indecisiveness, inability to take action.  Weakness of will.  Excessive tearing, drooling, salivation.  Visual and auditory hallucinations.  Inability to distinguish inner fantasy from outer reality.  Poor or slovenly hygiene habits.
     As mental disease progresses and one's mental condition deteriorates, things tend to gravitate towards the Yin and Yang extremes of the Choleric and Phlegmatic types listed above.  Traditionally, mental disorders were often attributed to possession by spirits, which were typically either violent, irritable and abusive (Choleric type) or passive, reclusive and delusional (Phlegmatic type).
     The mind is a great servant, but a terrible master.  Its purpose is to serve Soul in Its life experience, spiritual growth and unfoldment.  Mental disorders start the moment the mind takes over and takes direction and control away from the Soul.  As mental disease progresses, Soul has no choice but to stand by and watch the mind self-destruct as its mental karmas and predispositions play themselves out.
     Mental health and hygiene depend on knowing one's individual mental nature and temperament well enough to wisely avoid life activities, experiences, environments and challenges that would be too unsettling, unbalancing or overwhelming to one's psychic pepsis.  Life experiences, environments and activities are the food of the Psychic Faculty, and good mental hygiene depends primarily on a healthy balance of lifestyle factors.