Taoism is system of thought based upon the principles of yin and yang. It is often associated with the writing of Lao Tsu's (6th Century BCE), the Tao Te Ching

It is the basis of many practices arising from China such as Tai Chi, the I Ching, Traditional Chinese Medicine.

It is also incorporated with the the correspondences and the principles of yin and yang to treat the body, maximizing health (preventative but also curative). They have some similarity with Galen's Humoural system.

Spleen is a damp kitchen ,
liver is a tree,
lung is a bell,
heart is a firey engine,
kidney is a furnace.

The five elements

Yin and Yang "the primordial twin potencies" are the driving force behind all "ten thousand things" that exist within the universe.

-Yin is like the shaded side of the mountain, often seen as the force of darkness, of the cold or cool and of emptiness, peaceful entering, moisture energy, relaxed, smooth flow, descending energy, entering energy, earth, water, female....

-Yang is like the lighted side of the mountain, often seen as producing light, warmth and fullness, active energy, warm and dry energy, excited energy, ascending, sky, fire, male ....

Need to have both in Harmony - cannot have only one to dance the tango

-Body's surface is Yang (giving of energy) while the inside is yin (absorbing energy),
 like the Sympathetic and Parasympathetic divisions of the nervous system,
yang is full of energy and excitement, yin is relaxing and calming.

-The front of the body is yin and the back is yang

-Yin is in the five Ts'ang - liver, heart, spleen, lungs, and kidneys

-Yang is in the six Fu - gall bladder, stomach, large intestine,
small intestine, bladder and "warmer."

Pulse is controlled by yin and yang, manifesting both (used for assessment).
 

Diseases of the winter and spring are yin - taking away yang energy. 

Excess yin results in a "cold pattern" of cold hands and feet, pain in joints and pale or purple tongue with white coating and strong but slow and tight pulse.

Yin deficiency results in "empty heat pattern" such as hot flashes, dizziness, blurred vision. Pulse is fast, thin and weak.

  Diseases of the summer and autumn are yang - giving the body yang energy.

Excess yang results in "heat pattern" fever, thirsty, red face and eyes, yellow urine, Tongue is red with yellow coating pulse is strong full and rapid.

Yang deficiency results in pattern similar to excess yin along with deficiencies of fatigue, swollen tongue, low sexual energy. Pulse is slow, deep and weak.

Diet and activity affect one's body and spirit causes balancing or imbalancing of health and wellbeing. Likewise the physical environment can make people sick by having yin and yang thrown off due to greater energies.