Fu and the heart

The Chinese believed the heart was the center for happiness.
Even our modern society continues to put emotions under the control of the heart, speaking of having a broken heart when a loved one leaves, or stealing one's heart around Valentine's Day. These beliefs continued to be taught and taken as law until an English physician named William Harvey challenged them in the late 1620's.

From the Daoist classic, Contemplations by the Huainan Masters (Huainanzi) , ca. 110 B.C.:

The heart is the ruler of the five organ networks. It commands the movements of the four extremities, it circulates the qi and the blood, it roams the realms of the material and the immaterial, and it is in tune with the gateways of every action. Therefore, coveting to govern the flow of energy on earth without possessing a heart would be like aspiring to tune gongs and drums without ears, or like trying to read a piece of fancy literature without eyes.

From the Daoist classic, Guanzi, prior to 200 B.C.:

The heart is the emperor of the human body.
Its subordinate officers are in charge of the nine orifices and their related functions. As long as the heart remains on its rightful path,
the nine orifices will follow along and function properly.
If the heart's desires become abundant, however, the eyes will lose their sense of color, and the ears will lose their sense of sound. Thus it is said: 'Keep your heart empty-this is the art of the heart through which the orifices can be mastered.'
Deviation above will necessarily cause malfunction below. Do not race your heart like a horse, or you will exhaust its energy. Do not fly your heart like a bird, or you will injure its wings. Never frantically move things around just for the sake of seeing what will happen. If you move things around you dislocate them from their proper place. If you will be calm and patient, everything will come to you by itself.
The Dao is never far away, yet it may be hard to reach. It is within every one of us, yet it may be hard to grasp. If we stay clear of desires, the shen will enter its home. If we sweep away all impurities, the shen will stay with us.

Human beings all crave intelligence and wisdom, but rarely do we try to understand what the source of their existence is.

Alas, intelligence, intelligence-even if you jump over the ocean, it will not just sit there waiting for you! The seeker will be limping behind the one who is without desires. The sage does not seek anything, and thus naturally achieves the state of vacuous understanding [ultimate knowledge apart from fixed

And there is the luminous heart of spirit-shen-which generates qi and blood and thus is the root of life.

It is the source of all our bodily parts and functions, yet it does not manifest in obvious signs and colors. Just when you want to define it and say 'here it is,' it is gone; whenever you forget about it, however, it comes closer to you than ever. This is why it is called the 'vacuous spirit.' Despite its elusive nature, shen commands our body's every action and every part. Material form and luminous shen must therefore be looked upon as an interdependent pair, and we have to understand that diseases of the structural heart are always caused by unbalanced emotions such as depression, anxiety, obsession, or sadness, which open up a pathway through which noxious
pathogens can enter.From Li Ting, A Primer of Medicine (Yixue Rumen) , 1575

The ancient book of definitions [Neijing] refers to the heart as the ruler of the human body, the seat of consciousness and intelligence. If we decide to nourish this crucial element in our daily practice, then our lives will be long, healthy, and secure. If the ruler's vision becomes distracted and unclear, however, the path will become congested, and severe harm to the material body will result. If we lead lives that are centered around distracting thoughts and activities, harmful consequences will result.The sage regards his/her body like a country: the heart is the ruler, and the jing and the qi are the citizens. If the heart does not abuse its superior position, if it remains centered and focused on the essential matters, the jing will flourish and the qi will be steady, noxious intruders will always be fought off, the dantian will be full with treasures, and every part of the body landscape will be light and at piece.From Li Yuheng, Unfolding the Mat with Enlightening Words (Tuipeng Wuyu) , Ming dynasty, 1570:http://www.itmonline.org/5organs/heart.htm

Heart Heat Manifesting in the Small Intestine: Imbalances of zang organs frequently manifest as symptoms in their associated fu network. Thus, heart heat may manifest as burning diarrhea with intestinal cramping or burning urination (often with dark or red urine) that represents transfer of heat from small intestine to bladder. Conversely, small intestine heat can result in heart symptoms such as restlessness or mouth ulcers.
HEART AND KIDNEY FAILING TO LINK (xin shen bu jiao): primary symptoms are restlessness; insomnia; vivid dreaming; palpitations; forgetfulness; spermatorrhea or premature ejaculation. Secondary symptoms include dizziness; tendency to easily get startled; ringing in the ears; tidal heat sensations; night sweats; sore and weak lower back and knees; dry throat; flushed cheeks; dark and scanty urination or nocturia; constipation. The tongue typically presents with a red body and little or no coating; the pulse tends to be fine and rapid.