Spirit has three different meanings: 1) the creator, master, and original source of everything in the universe; 2) life activities including physiological functions and mental activities; and 3) consciousness and mental activities such as cognition, emotion, and will. Governed by the heart, spirit is primarily involved in human physiological functions and mental activities that pertain to five zang-organs respectively. Essence, qi, blood, and body fluids are the substantial foundations for spirit which is the result of movements, changes, and interactions among the essential qi of zang-fu organs.