years ago. In the various systems that were propounded by the leaders in medicine, principles that were more or less true in a limited field were taken to be of universal applicability. Medical science and art can not, however, be reduced to one or a few general causes, laws and formulas; each disease is a problem by itself, which must be worked out in all its aspects independently of other diseases. Hence the intellectual labors of a host of ingenious and talented thinkers for ages were wholly wasted, and effected no real advance in internal medicine, because they employed fallacious methods of thought.
Modern Medicine.—In the past seven or eight decades a radical transformation has taken place in internal medicine, pathology and therapeutics, which has put these subjects on the same high plane as any of the modern departments of science. There was no sharp dividing line of time between the old and the modern periods, but the new medicine developed gradually simultaneously with the decline of the old. The difference between the two depends on radical differences in logical method; modern medicine is developed by inductive, objective, empirical methods of attaining knowledge, the old doctrines were a product of theorizing and speculation. The evolution of modern scientific medicine has taken place along several independent lines of development.
The first branch of internal medicine to be elaborated on sound foundations was pathologic anatomy, its objective and obvious data making it facile of study. The pioneer in this branch was Morgagni (1682-1772) of Italy, whose epochal work on this subject appeared in 1761, when its author was 79 years of age. Other early workers in this field were John Hunter (1728-1793) of London and Bichat (1771-1802) of Paris. Bichat was followed by a brilliant group of French investigators during the first few decades of the nineteenth century, among the most eminent of which were Corvisart (1755-1821), Laënnec (1781-1826), Dupuytren (1777-1835), Andral (1797-1876), and Louis (1787-1872). The work of this group for a long time gave medicine a dominant pathologic-anatomical tone, especially in France.
The physical examination of patients by modern methods had its beginning in the introduction of percussion by Auenbrugger (1722—1809) of Austria. His method was published in 1761, but attracted no attention until it was revived by Corvisart (1755-1821) of France, who in 1808 published a translation of Auenbrugger's contribution which effectively brought it into use. The sister art of auscultation was introduced in 1819 by Corvisart's pupil Laënnec (1781-1826). Since that time there have been gradually developed the multitude of methods, physical, instrumental, chemical, microscopic and biologic, at present in daily use in the examination of the sick.
In the differentiation, clinical study and practical treatment of