Limited to 12. Invented in China at the end of the Ming dynasty and much refined thereafter, tai chi chuan has gained widespread popularity and recognition as the perfect exercise program for people of all ages. Research indicates that tai chi can play a significant therapeutic role in relaxation and rehabilitation. The movements are slow, without sudden or strenuous exertion, and precise, graceful, and powerful. They cultivate poise and grace, relax and tone muscles, and reduce nervous strain, leading to spiritual as well as physical relaxation. All the movements revolve about a unified principle of body motion that can be applied at every moment of daily life. Consistent practice is the key to proficiency in both the martial and the health aspects of tai chi ch'uan.