Book four of a study course on the philosophy and science of psycho-physical regeneration and longevity. This volume discusses regaining man's terrestrial paradise by regeneration through natural therapeutic agents. It contains eleven lessons entitled: preparation for the process of purification; regimens for the diet of purification; philosophy of the diet of regeneration and longevity; practice of the diet of regeneration and longevity; philosophy and practice of fasting, nature's greatest remedy; philosophy and practice of dynamotherapy; the healing, finer forces of nature; hydrotherapy or water cure; phytotherapy or herbology.