In this classic, concise study we are given a vivid picture of the human beings threefold nature, consisting of body, soul, and spirit. The author analyses the key aspects of our physical being and inner selves: the heart (organ of the heart quality), the metabolism (relating to the will), and the sensory-nervous system (as mirror of the soul). He provides a deeper understandingand hence a solid basis for workfor teachers, medical professionals and therapists, and anyone seeking encouragement to lead a healthy lifestyle.