She writes: "Traditional cultures which use herbs according to a theoretical system use herbs energetically. Chinese, East Indian Ayurvedic, Tibetan, Middle Eastern Unani and Native American Cherokee medicines are all founded on an energetic basis, although each system is different. To use herbs energetically, we look beyond the symptoms of the disease to alleviating the underlying imbalance which caused the disease. This cause varies according to each individual because all aspects of a person are taken into account, not just the disease itself."
In fact, Tierra looks beyond herbology in her holistic approach and notes what she considers five essential factors in the healing process: breathing exercises and contemplation; physical exercise; proper diet; appropriate lifestyle habits; and natural medicines. The book is divided into three parts, showing how to use herbs for health and healing, how to regain and maintain health, and how to obtain and make your own healing tools. She's also included a valuable bibliography, herbal resource guide, and a short piece written by her husband Michael Tierra on how her classification of yin and yang energy differs from that of macrobiotics as espoused by George Ohsawa.
Tierra's coverage of the energy of herbs and the energy of illness is one of the best I've found, and her success in explaining these concepts may lie in her straightforward, practical presentation which includes helpful charts and illustrations. Her theories are based on Traditional Chinese Medicine, simplified to a point but still comprehensive.