The Yellow Emperor's Inner Classic, the Neijing, has been a source book for traditional Chinese medicine for two thousand years. The Way of Heaven is a translation of the first two chapters together with a commentary. In Suwen chapter 1 the Yellow Emperor, Huangdi, asks why we no longer retain our vitality into old age. The answer given by his minister, Qi Bo, indicates that mankind no longer lives in harmony with heaven and earth. Following this declaration the seven and eight year natural cycles for women and men are described and discussed. Chapter 2 continues with an explanation of how we should live in tune with the four seasons, and explains behaviour appropriate to the time of the year. It introduces the concept of the five elements as resonances of the energies of the four seasons. Wide-ranging in their aim and scope, these chapters present a particular philosophy of health, emphasising the need to live in harmony with heaven and earth, in tune with natural cycles and stages of life. Following the way of heaven is the key to health and vitality, and losing the way the root of all pathology, both on an individual and planetary level.