Lester King has been a pathologist, teacher, practicing physician, and lifelong student of the history of medicine. In this forthright and scholarly work, he expresses his deeply felt conviction that there is a continuity in medical thinking--a bond linking the wisest clinicians today with Hippocrates, Galen, Vesalius, such lights as Herman Boerhaave of Leiden and William Cullen of Edinburgh, and those active in Paris and Berlin at the dawning of the age of germ theory and antisepsis. They were reasonable men, guided by observation and experience, who knew the difference between acting by ""reflex"" (automatically applying the current treatment to symptoms, as the ""empiric"" know-nothings did) and the search for patterns, individual differences, multiple causes of the patient's problems. The older generations were limited in technology; ""for illumination, only a candle."" Yet they raised many of the fundamental questions that medical science still asks: What is disease? What are facts? How do you classify disease? King illustrates his point with a fascinating history of tuberculosis before Koch's discovery of the tubercle bacillus. Today the ""mode of illumination has increased massively."" But visual acuity remains the same. And we still have doctors who practice ""reflex medicine""; who will more readily say that the treatment was insufficient (not enough antibiotics, etc.) and hence the patient died, than question the treatment itself. King makes a number of interesting, little-known points. The suggestion for controlled clinical trials, for example, was made numerous times over the past centuries and indeed was carried out by ship's surgeon James Lind in demonstrating (in 1753) that citrus fruits cured scurvy. Such details, plus King's repertoire of personal anecdotes, color the largely philosophical/semantical texture of the book. Chapters are devoted to the meaning(s) of disease, to causes, signs and symptoms, and classifications--as well as to the nature of facts and the scientific method. The style can get pedantic and repetitious; but King is always coherent. In his overall challenge to Lewis Thomas' assertion that, prior to the 1830s, ""the greater part of medicine was nonsense,"" he makes a remarkably good case. A corrective to glibness that, while accessible to all, would be especially valuable reading for medical students.