ADOLESCENCE is an artificial state, created by the demands of complex modem society for further education. Youth is prolonged by the requirements of training, apprenticeship, school, college and university, and those who are better intellectually endowed than others face a time of further education that may last from at least three to six years after leaving school. As such they are privileged by the opportunities they can enjoy-and the student who belongs to the educational elite of today can belong to the social elite of tomorrow's world. These privileged adolescents, however, have much need of un derstanding, sympathy, and help through the crises of develop ment, be they social, psychological or environmental in cause-because the student of today is the most precious investment for the community' sfuture. Whether it be problems of academic wastage, stress, depression, adjustment to personal relationships or the demands of just simply growing up, the privileged adolescent has a difficult time in contemporary society. If we, as parents, doctors, teachers, taxpayers and adults are responsible for making it any more difficult than it ought to be, by prejudice, lack of understanding or through not offering the right help at the right time, then we bear a terrible responsibility. Society will suffer for the harm it causes its adolescents and there are many who feel, perhaps justifiably, that addiction, promiscuity, suicide, depression and neurosis are symptoms of 'social illness' marked out by individual tragedy."

This book is designed for use by medical students, nurses, young practitioners, internists, family physicians and all those initially involved with the problem of diagnostics. It is struc tured to provide a concise logical approach to the diagnosis of common illness and disorders in adults. The elucidation of an illness cause is not easy for the inexperienced. Although text books and guidance notes can be referred to for clarification of assembled thought - once a medical history has been taken - a system-orientated reference guide has considerable value for aiding and checking the logic of diagnosis. It is hoped that this book will fulfil that purpose. It could not have been written without the help of R. G. Brackenridge's Essential Medicine (1979, MTP, Lancaster, England), and J. Fry's Common Diseases (1979, MTP, Lancaster, England), to which the reader is referred and to which generous acknow ledgement is made. The tables of Differential Diagnosis that follow Chapters 3-7 are adapted from some that have appeared in Handbook of Differential Diagnosis, vols 1-3, published by Rocom Press, Hoffman La Roche Inc., New Jersey, 1968-1974 - an invaluable publication now unfortun ately out of print, and permission to do so is gratefully apprec- 7 8 DIFFERENTIAL DIAGNOSIS iated. Finally without the stimulus and encouragement of Mr David Bloomer (MTP) and the particular assistance of Mrs J. C. Robinson, this book would never have been written. ALEXANDER D. G."