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414 conjure meaning out of facts by pretending to put an explanation upon them, that we will not ascribe the critical mood of the last generation to mere revulsion from the profuse hypotheses of the period when Chemistry promised to reveal the secret constitution of Nature; but, clearly, after a time of discovery and accumulation of facts, there comes the necessity for arrangement, classification, method, and the logician takes the place of the discoverer. To this work the generation of 1820-1850 set itself in no scholastic spirit, and one of its first achievements in the new field was Herschel's picturesque and elevated "Discourse." Ardent and imaginative as is that fine essay, it is nevertheless essentially logical. Four of his nine "rules of philosophizing" were converted by Mill into the experimental methods, and thus made a part of the logic of proof; his conception of a law is predominantly that of a generalization which seems to imply no inductive leap; and he appears to look for the openings to future discovery in the purely analytic direction of finding some more general laws of which the laws already discovered are cases. So faithfully did the work embody the tendencies of the period that its phraseology at once became classic, and its ideas of cause and law the commonplaces of science. They certainly formed a large portion of the mental pabulum of Mill, and are reflected, though with infinite widening and clarification, in the "System of Logic." We have already said that his four "methods" were but four of Herschel's "rules;" Herschel's "presumed permanence of the great laws of Nature" appears in Mill as the statement that "the uniformity of the course of Nature is the ultimate major premise in all cases of induction," and the relations of induction and deduction, the value and test of hypotheses, the nature of empirical laws, and the analysis of cause—are all striking aperçus which Mill pursued to their limits on every side, and thus was able to give to the exposition of them systematic completeness. All these conceptions, as being important parts of the logic of science, belong equally to the logic of psychology, and, if their statement in reference to mental science is due to Mill, the statement of them in reference to science generally is due to Herschel. But we are here more concerned to point out that the scientific conditions laid down by Mill as defining the logical status of psychology belong to the type of physical investigations of which Herschel was an early representative. The definition of science as having for its subject "uniformities," the description of the independence of a science as arising out of the irreducibility of its laws to other laws, and the exposition of the limits of scientific inquiry—all find their prototypes in the "Discourse." Here again, therefore, the advance in Psychology, though only logical, had its initiative in the physical sciences.

The rate of change quickens as the type of social structure rises, and the progress made by Psychology within the present generation