Circulation of the blood
Most people believe that the circulation of the blood in the body was discovered by William Harvey, and that it was he who first brought the idea to the attention of the world when he published his discovery in 1628. Harvey was, however, not even the first European to recognize the concept, and the Chinese had made the discovery two thousand years before.
In Europe, Harvey was anticipated by Michael Servetus (1546), Realdo Colombo (1559), Andrea Cesalpino (1571) and Giordano Bruno (1590). These men had read of the circulation of the blood in the writings of an Arab of Damascus, al-Nafis (died 1288), who himself seems to have obtained the idea from China. The writings of al-Nafis translated into Latin were lost, and rediscovered by a scholar as recently as 1956, establishing the source for Europe.
In China, indisputable and voluminous textual evidence exists to prove that the circulation of the blood was an established doctrine by the second century BC at the latest. For the idea to have become elaborated by this time, however, into the full and complex doctrine that appears in The Yellow Emperor's Manual of Corporeal Medicine (China's equivalent of the Hippocratic writings of Greece), the original notion must have appeared a very long time previously. It is safe to say that the idea occurred in China about two thousand years before it found acceptance in the West.
The ancient Chinese conceived of two separate circulations of fluids in the body. Blood, pumped by the heart, flowed through the arteries, veins and capillaries. Ch'i, an ethereal, rarefied form of energy, was pumped by the lungs to circulate through the body in invisible tracts. The concept of this dual circulation of fluids was central to the practice of acupuncture.
The Chinese traditionally identified twenty-eight different types of pulse, which they recognized as emanating from the pumping heart. The entire view of the body and its functioning was that of a dual circulation theory of blood (which was yin) and ch'i (which was yang). The two were interrelated. As a text dating from about the time of Christ says: 'The flow of the blood is maintained by the ch'i, and the motion of the ch'i depends on the blood; thus coursing in mutual reliance they move around.' The Yellow Emperor's Manual says: 'The function of the tract-channel system of the human body is to promote a normal passage [circulation] of the blood and the ch'i, so that the vital essentials derived from man's food can nourish the yin and yang viscera, sustain the muscles, sinews and bones, and lubricate the joints.'