Page:Popular Science Monthly Volume 28.djvu/363

Rh good even in the scientific sphere of prognosis; and who could deny the permanent value of many of the ethical, political, and historical speculations of the ages of Plato, Thucydides, and Aristotle, even though, according to the Comtist doctrine, sociological speculations should have been valueless at this time, because entirely premature?

The epoch of acquisition of facts, which must precede the discovery of their laws, often stretches over long periods of time—periods which interest us, because corresponding to the moment of education with which this discussion is concerned. The labors of the alchemists accumulated immense material on the composition of bodies and on their more recondite properties long before the scientific relations of chemistry could be established through the law of definite proportions. Physiology, the most complex of the physical sciences, has been most heterogeneous in the methods by which it has established its fundamental facts. The nature of respiration was, indeed, established by a chemist, from chemical data and from chemical experiments. But the nature of the circulation was partly inferred from anatomical facts—the presence of valves in veins—partly demonstrated by vivisection, a method of investigation which could not possibly be suggested by any other science than physiology. Knowledge of physics has materially assisted the interpretation of blood-pressure, of the expansion of the lungs, and many other phenomena, first known by direct observation of them. But the demonstration of the functions of the nervous system has been made exclusively by means of physiological experiment and clinical observation. "Science," observes Kenan, "in order to formulate her laws, is obliged to make abstractions and to create simple circumstances, such as Nature never presents." This is done usually with the aid of a simpler science, or one of wider generality, whose mastery thus becomes indispensable to further progress. But, until the moment for analysis and experiment has arrived, observation of the complex object is not more, but rather less difficult than that of the simple one, because in it so many varieties of details offer themselves spontaneously to the attention that the mind is at once fully occupied BO soon as it begins to carefully observe; whereas pure observation Boon exhausts the details of a simple object or phenomenon, and no further progress can be made until after a profound analysis has plunged below the surface. Let any one compare the rate of progress in the discovery of new knowledge in mathematics, astronomy, and even