[The importance of clinical observations for medical research]

Medical progress owes a great deal to the fundamental medical sciences and to the application of chemistry, physics and mathematics to medical problems. However, clinical observations and investigations are still of decisive importance in any field of medicine. By a feed-back mechanism they may even stimulate and fertilize fundamental medical sciences. Thus, our knowledge of the blood coagulation mechanism has been considerably enlarged by clinical analysis of hereditary bleeding disorders. - Chemotherapy of neoplastic diseases started from clinical observations during World War I (production of leucopenia by sulfur mustard gas). - Surgical procedures and their consequences have contributed greatly to our knowledge of thyroid function, of the segmental anatomy of the lung, and of the conduction system of the heart. - Observations of side effects of drugs have often enlarged or completely changed their primary clinical indications: from antibacterial sulfonamides, anti-diabetic, antihypertensive and powerful diuretic drugs have been developed, and from histaminics the modern neuroleptics and antidepressants. - Fundamental immunology has been enormously activated by clinical transplantation of kidney and bone marrow. Selective immunological defects in men, real experiments of nature, contributed much to our knowledge of the various types of allergic response. The quality of clinical investigations, particularly of controlled clinical trials, has been considerably improved during the last two decades. Although it is an applied science the reliability of its results is to-day comparable with that of "pure" natural sciences. However, medicine is more than a natural science: examples of outstanding scientists who at the same time were great and human physicians are presented.