The tendency of the nineteenth century seems to be a continuation, and, perhaps, in some respects, an exaggeration, of the condition obtaining in France during the previous century; in other words, the world has become practically an enormous school of pathological anatomy and diagnosis,--a school inaugurated by Bichat, as representing so-called scientific or exact medicine. Philosophically this has been a century of reaction against the idealism of the preceding age; it places the individual, rather than the idea, in the foregound. The mutual influence of medicine, philosophy, and the natural sciences is less conspicuous now than formerly. Recent philosophers who have exercised the greatest influence are: Schelling, who held to the equality of the real and the ideal; Hegel, whose supreme principle was absolute reason, of which religion was regarded as a representation; Hartmann, whose philosophy of the "unconscious" depends largely upon the results of natural sciences, embraces Darwinism, and is, in many respects, an extension and completion of Schopenhauer's{237} pessimism and doctrine of the soul. But one who has exercised still more influence upon our profession is Comte, whose positivism contrasted strongly with the idealism and atheism of Schelling, and who required only this of philosophy,--namely, that it should work out the general ideas and results of other sciences; his most important follower was Claude Bernard, and upon these two the whole exact school of France is based. But the most influential philosophic doctrines of this or any other century have been those emanating from Charles Darwin, Herbert Spencer, Ernst Haeckel, Alfred Wallace, and their contemporaries and followers. Darwin (1809-1882) was the grandson of Erasmus Darwin, already mentioned, and his _Variation of Animals and Plants Under Domes-tication, Origin of Species, and Descent of Man_ have found a place in all modern languages. The system known by his name is the pure science of nature, is founded upon scientific investigation, and by its merits alone has found almost universal acceptance; it has been added to and further elucidated by the efforts of Haeckel and Spencer. When it is declared that medicine of the present is influenced by no system, it is speedily found, on critical analysis, that this is an error. It necessarily follows the realistic and materialistic as readily as it did the teachings and doctrines of natural philosophy; and, in consequence, "medical thought," so called, is just as one-sided to-day as at any time in the history of the art. The watchword of to-day, natural specific tendency, veils, but does not take away, its philosophic principles, and so our ridicule of earlier medical systems is quite unjustifiable. A modern historian aptly remarks that the medicine of the present "embraces nothing but a theorem of investigation by the senses."