Biodynamic craniosacral therapy (BCST) is often regarded as the spiritual approach to craniosacral therapy (CST). In fact, BCST, as taught by Franklyn Sills, a pioneer in this field, is quite different from conventional CST. The biodynamic work is based on the development of perceptual skills, where the practitioner learns to sensitively respond to subtle breath movements known as primary respiration, as well as to the power of spontaneous healing. Through the breath of life, which Sills views as an echo of the Holy Spirit in the Judeo-Christian tradition, Bodhicitta in Buddhism, and Tai Chi in Taoism, BCST students learn to enter a state of presence that focuses on the client's innate ability to heal. In "Foundations in Craniosacral Biodynamics," Sills provides students and practitioners with a comprehensive, step-by-step guide to developing perceptual and clinical skills through specific clinical exercises.