Like often with Chinese Medicine concepts there is no ideal translation for what 'Shen' represents. Spirit and Mind are the translations most often used (we prefer Mind here) but it isn't a perfect equivalence.
For instance the concept of Shen doesn't include the Ethereal Soul (Hun) pertaining to the Liver; the Corporeal Soul (Po) pertaining to the Lungs; the Intellect (Yi) pertaining to the Spleen or the Will-power (Zhi) pertaining to the Kidneys. In the Western view of the mind, most people would agree it includes will-power and intellect...
What the concept does include are the general mental faculties of an individual: the capacity to form ideas, one's personality, one's memory, our affections, feelings, wisdom, etc.
The Mind, like other Vital Substances, is a form of Qi. In fact, it is Qi’s most subtle and least material type. One of the most important characteristics of Chinese Medicine is the close integration of body and Mind which is most transparent in the relationship between Essence (Jing), Qi and Mind, called the "Three Treasures".
Essence is the origin and biological basis of the Mind. The Mind of a newly conceived being comes from the Pre-Heaven Essences of its mother and father. Stored in the Kidneys, it provides the biological foundation for the Mind at the very beginning of one's life. This is why Essence is often referred to as "the root of the Mind".
After birth, however, the Mind also depends on the nourishment from Post-Heaven Essence and Qi produced by the Stomach and Spleen. If Essence and Qi are depleted, the Mind will suffer and may become unhappy, depressed, anxious, or clouded.
In typical Chinese Medicine mutual relationship, the corollary is true as well: if the Mind is disturbed by emotional stress, becoming unhappy, depressed, anxious or unstable, it will definitely affect Qi and/or Essence. In most cases it will affect Qi first since emotional stress upsets the normal functioning of Qi. Emotional stress will tend to weaken the Essence either when it is combined with overwork and/or excessive sexual activity, or when the Fire generated by long-term emotional tensions injures Yin and Essence.
Regardless of the amount of Mind (Shen) one is born with, it is after birth that Mind (Shen) can be diminished or obliterated if nourishment by the Heart Qi and Blood does not continue. The Gate of Fire (Ming Men) in the Kidneys also influences this as it manifests the level of will-power and determination that assists the Heart in housing the emotions and Mind. If either Heart Blood, Qi or the Gate of Fire are Deficient, then Mind (Shen) becomes depleted. When Mind (Shen) is weak, Spirit and the mental capacities decline. There may be muddled thinking, forgetfulness, insomnia, lack of vitality, depression, lack of interest in life, unhappiness, confused speech or excessive dreaming.
In the extreme, a Mind (Shen) disharmony can result in irrational behavior, unconsciousness, incoherent speech, hysteria, delirium, inappropriate responses to people or the environment, or violent madness. Disharmonies of Mind (Shen) can also occur from excessive Heat in the body. In this case it causes "reckless movement" with any of the above symptoms resulting.
Mind (Shen) resides in the Heart and, as one might imagine, encompasses more than physical Heart functions. There has to be some explanation why the Heart is closely linked to emotions in so many traditions around the world. In popular English jargon we have terms like 'heartfelt gratitude', 'broken heart', 'cold-heartedness', etc.
This intuitive connection seems ignored by Western Medicine but in the psycho-spiritual aspect of Chinese Medicine the Mind (Shen) in the Heart is often the real cause for what gets classified under broad 'Heart diseases' in the West. If there is an epidemic of Heart diseases in the West, perhaps it's not only about blocked arteries and defective valves, there might also be a spiritual/emotional component there.
As the 'Heart rules the Mind', its health influences our capacity to think clearly, behave appropriately, discriminate, be responsive, speak coherently and experience happiness and profound joy.
In Chinese Medicine emotions are distributed over our various Organs but they all end up affecting the Heart because only the Mind (Shen) can ‘feel’ affections and feelings. It alone, being responsible for consciousness, affection and feelings, can recognize and feel the effect of emotions.
Fei Bo Xiong (1800–1879), a famous Chinese doctor, wrote: ‘The seven emotions injure the 5 Yin Organs selectively, but they all affect the Heart. Joy injures the Heart. Anger injures the Liver, but the Liver cannot recognize anger but the Heart can, hence it affects both the Liver and Heart. Worry injures the Lungs, while the Lungs cannot recognize it but the Heart can, hence it affects both the Lungs and Heart. Pensiveness injures the Spleen, but the Spleen cannot recognize it but the Heart can, hence it affects both the Spleen and Heart.’
The way that all emotions afflict the Heart also explains why Heart Fire indicated by a red tip of the tongue is so commonly seen even in emotional problems related to other Organs than the Heart.
All senses (sight, hearing, smell, taste and touch) depend on the Mind (Shen) in much the same way as they depend on the brain in Western Medicine
In Chinese Medicine each sense is related to a certain Organ: smell to the Lungs, taste to the Spleen and Heart, hearing to the Kidneys and sight to the Liver. However, all senses rely also on the Heart because it is the Mind that ultimately receives the sensory perceptions.
The eyes and sight are obviously related to the Liver, especially Liver Blood, and the Ethereal Soul. However, although the eyes rely on the nourishment from Liver Blood, Blood flows to the eyes through Blood vessels which are under the control of the Heart. Wang Ken Tang, in ‘Standards of Diagnosis and Treatment’ (1602) says: ‘The eye is an orifice of the Liver … but a function of the Heart.’ In fact, Chinese Medicine views excessive use of the eyes as harmful to the Blood vessels and the Heart. This explains the damaging effect of excessive TV watching on the eyes and the Mind in children.
Hearing depends on the Kidneys but the Heart also has an influence on it because the Heart brings Qi and Blood to the ears. Some types of tinnitus are due to Heart Qi being Deficient and not reaching the ears.
The sense of smell is also dependent on the Heart and Mind (Shen) together with the Lungs. A Chinese Medicine saying goes: ‘The five odors enter the nose and are stored by the Lungs and Heart; if the Lungs and Heart are diseased, the nose cannot smell.’
The sense of taste naturally depends on the Heart and Mind as the tongue is an offshoot of the Heart. Same for the sense of touch which is also directly dependent on the Heart and Mind (Shen) as this is responsible for the cognition and organization of external stimuli sensations.
This encompasses the totality of thoughts and perceptions as well as the state of being conscious. This is the most important of the Mind’s functions. The Mind(Shen) residing in the Heart is what makes us conscious as human beings, what gives each of us a sense of being an individual. In psychological terms, we may compare the Mind (Shen) with the ego consciousness.
The Mind (Shen) is responsible for the recognition of thoughts, perceptions and feelings. When the Mind is clear, we are conscious; if the Mind is obfuscated or suddenly depleted, we lose consciousness.
They depend on the Mind (Shen) because only the Mind (and therefore the Heart) can ‘feel’ them. Here ‘affections’ means the normal range of affective feelings which all human beings experience. The term ‘emotions’ are affections that, due to being intense and prolonged, become causes of disease.
Of course affection and emotions definitely affect all the other Organs too, but it is only the Mind(Shen) that actually recognizes and feels them. For example, anger affects the Liver, but the Liver cannot feel it because it does not house the Mind. Only the Heart can feel it because it houses the Mind, which is responsible for insight. It is for this reason that all emotions eventually affect the Heart (in addition to other specific Organs), and it is in this sense that the Heart is the ‘emperor’ of all the other Organs.
If the Mind is strong, thinking will be clear. If the Mind is weak or disturbed, thinking will be slow and dull. The Chinese characters for ‘thought’ (意, Yì), ‘to think’ (想, Xiang) and ‘pensiveness’ (思, Sī) all have the character for ‘Heart’ (心, Xīn) as their radical.
In Chinese Medicine, memory can mean two bodily functions: our capacity to memorize data when one is studying or working and the ability to remember past events. Both of these depend on the Mind and therefore the Heart, although to some extent also on the Spleen and Kidneys (respectively housing our Intellect - Yi - and Will-Power - Zhi).
This describes our capacity for self-knowledge and self-recognition. We are subjected to many different emotional stimuli, perceptions, feelings and sensations and all of these are perceived and recognized by the Mind. Insight is lost when the Mind is obstructed by Phlegm, resulting in serious mental illnesses such as psychosis.
Our capacity for higher mental processes, memory, language, problem solving and abstract thinking.
In Chinese Medicine sleep is dependent on the state of the Mind. If the Mind is calm and balanced, a person sleeps well. If the Mind is restless, the person sleeps badly.
A strong Heart and Mind will make a person intelligent and bright. A weak Heart and Mind will render a person slow and dull. It should be remembered, however, that the Essence, and therefore heredity, plays a role in determining a person’s intelligence.
Wisdom derives from a strong Heart and a healthy Mind. As the Mind is responsible for knowing and perceiving, it also gives us the sagacity to apply this knowledge critically and wisely.
Generating ideas is another function of the Mind. The Heart and Mind are responsible for our ideas, our projects and the dreams that give our lives purpose. However, the Ethereal Soul (pertaining to the Liver) also plays an important role in this area.
It is the Mind that recognizes the stimuli generated by perceptions, touch, taste, pressure, temperature.
In diagnosis of disease, the appearance of Mind (Shen) is an important factor and is one of the first signs noted in examination of a patient along with tongue and pulse. No matter how ill a person is, if the eyes glitter and sparkle, there is luster in the face, the tongue looks bright and flourishing, or the personality is in 'good spirits' or has vitality, then Shen is present and recovery is easier and more certain.
On the other hand, no matter how simple the illness, if the eyes lack life or sparkle, the face is dull and cloudy or the person lacks interest in life, recovery may be difficult and the prognosis is poor. Sometimes during the last stage of a severe or terminal illness a person suddenly becomes alert, more positive and vital. It is termed 'false Shen' because it is the last desperate spark of spirit manifesting before the life force separates from the body.
Because Mind (Shen) is so closely linked to the Heart, it is not distinguished by pathologies of its own. Instead, symptoms are differentiated as the Heart pathology categories of Deficient Heart Blood, Heart Fire and Cold or Phlegm Misting the Heart. However, one must keep in mind that Shen problems are spiritual problems and a true Chinese doctor must eventually develop the skills to address such spiritual issues on their own terms. This is done through life counseling (compassionately listening and responding with the right word at the right time), affirmation, meditational practices that are given to the patient and recommendations to play more, change jobs, take a holiday and whatever else is needed to nourish the spirit and Heart.