its qualities and gains others by mixing and blending (13.3). Human beings are affected by the food they consume because every food has its own innate virtues. It is important for the physician to identify these virtues (14.1-2). The attainment of such knowledge demands a clear understanding of human nature. The human being, explains the author, contains a blend of many humors. When the humors are balanced or properly mixed the human being is healthy, but when they are unbalanced or improperly mixed and one is more concentrated than the other, pain and disease is the result (14.4-6). In chapter 15 the author argues that whereas the proponents of humoral medicine see food purely as hot, cold, wet, or dry, human beings also possess a quality such as sweet or bitter. These qualities are the ones that cause serious harm to the body. In Chapter 16, the author presents a number of examples from common experience. For instance, in a fever hot and cold humors counteract each other in the body without the need of medical aid. As he points out in chapter 17, however, in some cases the fever persists. This is an indication that hot is not the sole cause of the fever. There must be some other inherent factor responsible for sustaining the fever. In chapters 18 and 19, he continues to develop the idea that recovery from disease comes about when there is a blending and coction of the humors. Coction is the act or process of attaining a more perfect or more desirable condition. The importance of coction in the author's theory also reflects his close analogy between medicine and cooking. Just as the cook brings about coction in food external to the human organism; the physician brings about coction of the bodily humors. Chapters 20–24 In chapter 20 the author dismisses the theories of human nature associated with Empedocles and the pre-Socratic inquiry as irrelevant to medical practices. He argues that their theories lean towards philosophy and have more to do with the art of writing than with medicine. The author believes that the theory of human nature must be based on medicine, through the observation of the human organism within nature. He takes exception to thinkers such as Empedocles who attempted to provide such an understanding through his cosmological theories. Practically speaking, for medicine to be effective the physician needs to know the