The Tai Chi Concepts and Experiments book clarifies and makes accessible critical aspects of the art that only a small number of high-level practitioners currently understand and manifest. Numerous step-by-step experiments are provided for readers to experience and perfect these critical tai chi aspects. Contents include: The meaning and importance of releasing tension in movement for stability, health, and spirituality. The differences between contractive and expansive strength including a promising mechanism for the nature of expansive strength. Numerous experiments for readers to recognize and experience expansive strength and to confirm that they have achieved it. Elucidation of famous master's sayings on mind, strength, and chi. Health and martial advantages of expansion over contraction in tai chi. Protocols using expansion including those for helping an excess curvature of the upper and lower spine and for relieving plantar fasciitis. Quotes from the classics and how they confirm the interpretations of the principles of tai chi. How to achieve optimal balance through an understanding of physical, anatomical, physiological, and mental factors. A detailed analysis of "rooting and redirecting" including physical and internal aspects. Understanding natural movement from physical, philosophical, health, and martial points of view. This interdisciplinary book utilizes, elementary physics, physiology, anatomy, psychology, and spirituality. It contains detailed analyses and explanations for achieving internal, expansive strength, known as nei jin, and for attaining optimal timing and natural movement.