a child, persuading too often by ardent insistence rather than by logical proof. His students were thus passive learners, even where the teaching was demonstrative. They studied anatomy by watching a teacher dissect; they studied therapeutics by taking the word of the lecturer or of the text-book for the efficacy of particular remedies in certain affections.
The third era is dominated by the knowledge that medicine is part and parcel of modern science. The human body belongs to the animal world. It is put together of tissues and organs, in their structure, origin, and development not essentially unlike what the biologist is otherwise familiar with; it grows, reproduces itself, decays, according to general laws. It is liable to attack by hostile physical and biological agencies; now struck with a weapon, again ravaged by parasites. The normal course of bodily activity is a matter of observation and experience; the best methods of combating interference must be learned in much the same way. Gratuitous speculation is at every stage foreign to the scientific attitude of mind.
We may then fairly describe modern medicine as characterized by a severely critical handling of experience. It is at once more skeptical and more assured than mere empiricism. For though it takes nothing on faith, the fact which it accepts does not fear the hottest fire. Scientific medicine is, however, as yet by no means all of one piece; uniform exactitude is still indefinitely remote; fortunately, scientific integrity does not depend on the perfect homogeneity of all its data and conclusions. Modern medicine deals, then, like empiricism, not only with certainties, but also with probabilities, surmises, theories. It differs from empiricism, however, in actually knowing at the moment the logical quality of the material which it handles. It knows, as empiricism never knows, where certainties stop and risks begin. Now it acts confidently, because it has facts; again cautiously, because it merely surmises; then tentatively, because it hardly more than hopes. The empiric and the scientist both theorize, but logically to very different ends. The theories of the empiric set up some unverifiable existence back of and independent of facts,—a vital essence, for example; the scientific theory is in the facts,—summing them up economically and suggesting practical measures by whose outcome it stands or falls. Scientific medicine, therefore, has its eyes open; it takes its risks consciously; it does not cure defects of knowledge by partisan heat; it is free of dogmatism and open-armed to demonstration from whatever quarter.
On the pedagogic side, modern medicine, like all scientific teaching, is characterized by activity. The student no longer merely watches, listens, memorizes; he does. His own activities in the laboratory and in the clinic are the main factors in his instruction and discipline. An education in medicine nowadays involves both learning and learning how; the student cannot effectively know, unless he knows how.
Two circumstances have mediated the transformation from empirical to scientific medicine: the development of physics, chemistry, and biology; the elaboration out of them of a method just as applicable to practice as to research. The essential de-
