The sayings in t'ai-chi theory that yin cannot do without yang, yang cannot do without yin, yin and yang help each other, "the more you are lax the stronger you are," "void and solidity should be clearly separated, each has its own place ..." all are developments of the essential thought of the I Ching.
例如，站立時用手推車，怎樣也推不動；如稍微蹲下身子，就容易推得多。以靜制動，以逸待勞，以柔克剛太極拳講究「以靜制動」，但並非不動，而是「伺時、伺機」才動。