Qi is one of the vital substances that humans need to live happy and healthy. Nevertheless, the human body needs other substances such as blood, fluids, essence, spirit mind. All the vital substances circulate in the meridian channels. Each of these substances performs an important function in the body, therefore these five vital substances (that were mentioned) work together to help the body and mind be in a state of peace and well-being (Ody 34).

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• Qi (Vital Energy):

Qi is the energy of the universe. In our bodies, Qi is the energy that maintains us alive. Without Qi, we wouldn’t live. Qi makes sure that everything in our body is working in balance, as well as it is directly responsible for our strength, keeps our body warm, our metabolism and our digestion. It also protects us from diseases, and it attacks diseases. Qi is basically formed by the food we eat and the air we breathe. Hence, humans have to make sure that they are eating healthy food and that they are breathing clean air if they want to have a strong Qi (Hafner).

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• Blood:

In Chinese medicine, blood is considered the substance that nourishes and refreshes our body and mind. It is also the substance in which Shen (which is our spirit) is contained. Qi and blood perform many of the same functions and they are interdependent (Hafner).

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• Fluids:

Fluids are one of the vital substances because they moisten and lubricate our body which is necessary for the balance in our body. Some of the fluids are tears, saliva, semen, mucus, or breast milk (Hafner).

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• Essence:

Essence influences growth, development, longevity and reproduction of our body. It proceeds of two sources (Ody 38).

• Congenital essence: Which is the essence that is inherited from the parents, its quantity is set and it cannot be changed. However, it is timeworn, and this causes the aging.

• Postnatal essence: Every person gets their essence in the simple and in the unconscious actions such as eating, drinking, breathing. Therefore, everything that we do has an important influence in our essence which is responsible for important functions in our body.

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• Spirit mind:

In the western culture, the body and the spirit are considered separate things. However, in Chinese perspective, this division doesn’t exist, so the body and the spirit are viewed as one. Shen is responsible for our consciousness, understanding, mental health and our perceptions. Shen is located in the blood vessels and it can be detected through the brightness of a person’s eyes. Therefore, when a person has a low brightness in his or her eyes, it means that he or she has a lack of Shen which could cause insomnia, confusion, emotional problems etc.  That is why people say that the eyes are the windows to the soul (Ody 40).