The Evolution of the Concept of Disease

PRESIDENT'S ADDRESS By Professor Sir HENRY COHEN, M.D., D.Sc., LL.D., F.R.C.P. "THE very purpose of philosophy", wrote Whitehead in his "Adventures of Ideas", "is to delve below the apparent clarity of human speech". The dominant trends in contemporary philosophy have been fashioned and profoundly influenced by semantic studies; they reject the Baconian precept that the study of words is "the first distemper of learning". In medicine there are innumerable examples of words whose meaning has altered with the passage of time and increasing knowledge. For example, "artery" persists from the pre-Galenic days when that vessel was thought to contain air (cahp = air; T7-rpeLv to keep); the "phrenic" nerve supplied the diaphragm which was then regarded as the seat of the mind (Gk. 4,pfvr= mind); the "pituitary" gland owes its name to the mistaken notion that it secretes the nasal mucus (L. pituita = phlegm); the very different pathological states of osteomyelitis and myelitis share their common etymology from the days when the spinal cord was thought to be the bone-marrow (Gk. ,iveXos) of the vertebral column. These words, and an infinity of others, have varied in meaning with changes in contemporary knowledge and theory; their colour and content reflect the knowledge of the' times in which they were introduced. The word "disease" is no exception to this general rule. The notion or concept which it conveyed has varied with the ideas held about the nature of disease through the ages., The differentiation of disease as dis-ease, with its pain and suffering contrasted withi health (G.E. hal = whole) has been recognized from the earliest times, though its existence has been denied by the Stoics in ancient times and, more recently, by quasi-religious; cults. Primitive man was not deeply concerned with the nature or cause of disease. He sought its cure. And his purpose was not wholly selfish; sympathy for his fellows is revealed in his writings as one of the dominant human instincts. The cures which he elaborated were based on crude supernatural magical doctrines, all of which, however, profoundly influenced later thought. Of these principles, those most widely known were the doctrines of similars, of signatures, of analogy, and of contagion. The doctrine of similars was based on the principle that objects or circumstances similar in shape, colour, or sequence of events to those preceding or resulting from disease were effective in its treatment. For example, the appropriate remedy for greying hair was stewed raven because of its deep black features, whilst yellow birds were useful for jaundice.1 Those who based their practice on the doctrine of signatures, and it had a long sways claimed that plants and animals have distinctive marks which indicate their medicinal properties. Thus trefoil was used in heart disease; the yellow celandine in jaundice; cyclamen for ear disease; flowers of the lily for gout; the-roots of bryony (which resembled a swollen foot) for dropsy; thistle for a stitch in the side; walnut shells for head injuries; the spotted skin of the lizard for tumours. This doctrine was later to be the main basis of the therapeutic systems of Paracelsus and Culpeper. The doctrine of the analogy had a more modern ring. The behaviour of ailing animals was observed, the food they took, whether, where and when they rested. Similar measures were then adopted in cases of human illness. Later, analogy was extended, to ill people. Special attention was paid to what happened to those who recovered. From analogy there came many useful contributions to knowledge; but it saw the birth in medicine of the post hoc ergo propter hoc fallacy whose baneful effects still influence treatment. The doctrine of contagion was more recondite and took account of the alleged cause of disease. The object used in treatment was one which had been associated with this cause, for example, moonstone in mental disorders. Except for the doctrine of contagion none of these principles of treatment was based on. theories concerning the nature of disease. From the earliest times to the present day two main concepts have dominated all writings on the nature of disease. These are (i) disease. as a distinct entity; when a healthy man A falls ill he becomes A plus B, where B is "a disease". This view maintained that there are innumerable Bs, each with its individual and recog"lThis doctrine differs from that of Hahnemann's similars-similia similibus curantur-in that here a drug is advocated because it gives symptoms and signs similar and peculiar to those whic4, the patient manifests. Hippocrates reveals his acceptance of this doctrine m the use of veratrun, but his writings show him as an eclectic who did not confine his therapy to one system.