Hence, secondly, he was led to define certain methods or canons of induction. It was Bacon who first called attention to the importance of "glaring" or "striking" instances, in which the phenomenon under investigation is thrown into relief; "parallel" instances, which permit of the argument from analogy; and "crucial" instances, which serve as tests of contrary hypotheses. From Bacon, Mill derived the methods to which he gave such prominence in his Logic, the methods, namely, of "agreement," "difference" and "concomitant variation." By means of these methods it is possible to single out from among the circumstances attending or preceding the phenomenon to be explained, that which is its probable cause. That which is present when the phenomenon is present, which is absent when the phenomenon is absent, and which shows like quantitative changes, may be assumed to be connected with the phenomenon, and to point the way to its explanation.
But, thirdly, it is necessary to supplement observation of the natural course of events with artificial experiments. Nature, like men, will reveal her secrets only when put to the torture. Bacon was a consistent advocate of the first-hand manipulation of natural bodies. He saw this to be the only method of study which afforded any prospect of laying bare the more "subtle" physical phenomena, such as heat, light and the transmutation of substances. The later development of physics and chemistry not only confirmed this judgment, but in several signal cases fulfilled definite predictions which Bacon based on it.
Fourthly, Bacon recommended the comparative and historical method. He was one of the first to appreciate the importance of studying all phenomena that develop, in different stages of their development. In the particular case of anatomy, he called attention to the importance of studying the structure of organs in their simpler forms, and using the results as a key to the complex forms.
V. The Baconian Pragmatism.—Bacon's extraordinary modernism appears not only in his definition of sound and fruitful methods of scientific study, but also in his conception of the relation of science to civilization. And in nothing is he so modern as in this. He asserted that the hope of man lay in his advancing knowledge and control of nature. This idea is undoubtedly a present commonplace, but there are few philosophers that anticipate the commonplaces of mankind by three centuries and a half! But the idea is too fundamental properly to be called a commonplace. It is the most fruitful idea in modern life, the main presupposition of progress. Bacon sought to promote learning for the sake of power. That this is essentially a modern idea will be apparent to any one who will study the motives underlying earlier periods of European civilization. The ancient world had its critical and its dogmatic idea of progress. The
