Health Health could be defined theoretically in terms of certain measured values for example, a person having normal body temperature, pulse and breathing rates, blood pressure, height, weight, acuity of vision, sensitivity of hearing, and other normal measurable characteristics might be termed healthy. But what does normal mean and how is it established? It is well-known that if the temperatures are taken of a large number of active, presumably healthy, individuals the temperatures will all come close to 98.6°F(37℃). The great preponderance of these values will fall between 98.4°F and 98°F. Thus health could in part be defined as having a temperature within this narrow range. Similarly, a normal range can be established for pulse, blood pressure, and height. In some healthy individuals, however, the body temperature may range below 98.4°F or above 98.8°F. These low and high temperatures fall outside the limits defined above as normal and are instances of biological variability. Health might better be defined as the ability to function effectively in complete harmony with one's environment. Implied in such a definition is the capability of meeting physically, emotionally, and mentally—the ordinary stresses of life. In this definition health is interpreted in terms of the individual's environment. Health to the construction worker would have a dimension different from health to the bookkeeper. The healthy construction worker expects to be able to do manual labour all day, while the bookkeeper, although perfectly capable of performing his own sedentary work, would be totally incapable of such heavy labour and indeed might collapse from the physical strain yet both individuals might be termed completely healthy in terms of their own way of life. The term physical fitness, although frequently used, is also exceedingly difficult to define. In general it refers to the state of optimal maintenance of muscular strength, proper function of the internal organs, and youthful vigour. The champion athlete prepared to cope not only with the commonplace stresses of life but also with the unusual illustrates the concept of physical fitness. To be in good physical condition is to have the ability to swim a mile to save one's life or to slog home through snow drifts when a car breaks down in a storm. Some experts in fitness insist that the state of health requires that the individual be in prime physical condition. They prefer to divide the spectrum of health and disease into (1) health, (2) absence of disease, and (3) disease. In their view, those who are not in prime condition and are not physically fit cannot be considered as healthy merely because they have no disease. Healthy involves more than physical fitness, since it also implies mental and emotional well-being. Should the angry, frustrated, emotionally unstable person in excellent physical condition be called healthy? Certainly he could not be characterized as effectively functioning in complete harmony with his environment. Indeed, such an individual is incapable of good judgment and rational response. Health, then, is not merely the absence of illness or disease but involves the ability to function in harmony with one's environment and to meet the usual and sometimes unusual demands of daily life. The definitions of illness and disease are equally difficult problems. Despite the fact that these terms are often used interchangeably, illness is not to be equated with disease. A person may have a disease for many years without even being aware of its presence. Although he is diseased, he is not iii. Similarly, the diabetic person who has known disease and has received adequate insulin treatment is not ill. The cancer victim is often totally unaware of his disorder and is not ill until after long years of growth of the turnout, during which time it causes no symptoms. The term illness implies discomfort or