Functions of the Heart
The Heart houses the spirit (Shen).
Commentary: The Heart houses the spirit. This means the Heart is the seat of consciousness and mental activity. The Heart depends on the supply of sufficient Yin and Yang to give the spirit a surrounding in which it can flourish. The Heart possesses abundant Yang but little Yin, so that it is especially susceptible to Yin Deficiency. Yin Deficiency causes the spirit to be deprived of its dwelling place. The spirit becomes restless. The Blood is the root of the spirit, it surrounds and anchors the spirit, so that the spirit is at peace and can be happy. Heart Blood Deficiency causes the spirit to be restless; it leads to depression, fear, excessive dreaming and insomnia. In the same manner can unrest, depression and emotional problems affect the Heart and lead to Heart Blood Deficiency.