Yin-Yang Theory

The Yin-yang theory represents the most profound philosophical theory conceived by ancient Chinese philosophers. Joseph Needham, a famous historian of science, believed that this theory “was the most ultimate principle of which the ancient Chinese could conceive”. Scholars specializing in ancient culture, ideology, philosophy, and history of science widely acknowledge the crucial role of the yin-yang theory in fostering the development of traditional Chinese medicine. Also, this theory was extensively applied and developed in ancient Chinese medicine. However, it is worth considering whether there exists any difference between the “yin-yang theory” developed by the yin-yang school of the pre-Qin period (before 221 BC) and the “yin-yang theory” in traditional Chinese medicine.