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.