tion, that is, a definition based either on the nature or essence of the thing defined, or on its distinctive attributes. Disease is an absence or deficiency of health; but this is only to transfer the difficulty, for the question at once arises, how is health to be defined? And to define health is not less difficult than to define disease. If all the tissues and organs of the body have their normal integrity and properties; if the fluids of the body are in no respect abnormal; if all the functions of the organism are completely and harmoniously performed, health undoubtedly exists. But this perfection of health is purely ideal; it never actually exists. An examination of the bodies of the healthiest persons would probably reveal lesions of some kind; certain deviations from the normal composition of the different fluids are not inconsistent with the evidences of health in other respects; functions of different parts may be disordered to a certain extent without sufficient disturbance to constitute disease. Gradations of health are implied in the qualifications of this term in common use. If the term health expresses a well-defined state, it would be a pleonasm to add to the term, as is often done, the adjectives good, excellent, etc; and, on the other hand, to speak of health as poor, bad, miserable, etc., would involve a solecism. In short, health and disease are so imperceptibly merged into each other, that the line of demarcation cannot be drawn with precision. And this is true of other departments of knowledge. It is not easy, for example, to settle upon the characters which mark the boundaries of the animal and vegetable kingdoms. But as there is rarely any practical embarrassment in distinguishing an animal from a vegetable, so with regard to health, if an important disease of any kind exist, the fact of its existence is in most cases sufficiently obvious. If, however, it be desirable to define disease otherwise than by saying that it is the absence or deficiency of health, the definition proposed by Chomel is, perhaps, as good as any other. According to this author, disease may be defined to be a notable disorder affecting more or less of the constituent parts of the living organism, either as regards their material constitution or the exercise of their functions.' Regarding disease as the absence or deficiency of health leads to the consideration of the relationship of Pathology to Physiology. Physiology studies. the operations which go on in the healthy organism. The morbid conditions which are the subjects of pathological study are these operations disordered or perverted. Pathology has been called morbid physiology. Both are, in fact, parts of one science, the science of life, or biology. Both are alike occupied with vital properties, actions, and processes, the difference being that physiology investigates them under the circumstances of health, and pathology under the circumstances of disease. The division is arbitrary, although sufficiently marked and appropriate. Such being the relationship of pathology to physiology, it might be expected that the former would advance in proportion to the progress of the latter. This is measurably true. While our knowledge of pathological conditions does not consist of deductions from what is known of the operations within the organism in health, but is derived from the direct study of disease, every important physiological discovery sheds more or less light on the department of pathology. In striving to penetrate into the nature of morbid conditions, it is evident that the chief difficulty arises from the imperfection. of our knowledge of the properties, actions, and processes of health. There "Un désordre notable survenu, soit dans la disposition matérielle des parties constituentes, du corps vivant, soit dans l'exercice des fonctions." For an enumeration of the various definitions proposed by different writers, and some excellent remarks on the subject, this author may be consulted: Elémens de Pathologie Générale, quatrième édition. will be frequent occasions, in the progress of this work, to remark that the pathologist may expect to be better able to explain the phenomena of disease when the physiologist has succeeded in elucidating more fully the phenomena of health. In proceeding now to present the outlines of medicine, the aim of the author will be to give a truthful representation of pathological knowledge as it exists at the present moment. The progress of pathological knowledge has wrought, within the few past years, much change in both the principles and practice of medicine. Concerning further progress and its effects, it would be in vain to speculate; but it is hardly to be expected that a faithful exposition of medicine as it exists at the present moment will serve as a lasting guide for the student and practitioner. And in the study of medicine, next in importance to an acquaintance with what is actually known is a just appreciation of the limits of our present knowledge. The latter is often important as regards its bearing on the treatment of disease, and it conduces to a condition of mind most favorable for either contributing to, or keeping pace with, the continued progress of knowledge. |