In the seventeenth century a newly emancipated and too sanguine reason proposed to know the whole of nature at once in terms of mathematics and mechanics. Thus the system of the Englishman Hobbes was science swelled to world-proportions, simple, compact, conclusive, and all-comprehensive. Philosophy proposed to do the work of science, but in its own grand manner. The last twenty years of Hobbes's life, spent in repeated discomfiture at the hands of Seth Ward, Wallis, Boyle, and other scientific experts of the new Royal Society, certified conclusively to the failure of this enterprise, and the experimental specialist thereupon took exclusive possession of the field of natural law. But the idealist, on the other hand, reconstructed nature to meet the demands of philosophical knowledge and religious faith. There issued, together with little mutual understanding and less sympathy, on the one hand _positivism_, or exclusive experimentalism, and on the other hand a rabid and unsympathetic transcendentalism. Hume, who consigned to the flames all thought save "abstract reasoning concerning quantity or number," and "experimental reasoning concerning matter of fact and existence"; Comte, who assigned metaphysics to an immature stage in the development of human intelligence; and Tyndall, who reduced the religious consciousness to an emotional experience of mystery, are typical of the one attitude. The other is well exhibited in Schelling's reference to "the blind and thoughtless mode of investigating nature which has become generally established since the corruption of philosophy by Bacon, and of physics by Boyle." Dogmatic experimentalism and dogmatic idealism signify more or less consistently the abstract isolation of the scientific and philosophical motives. There is already a touch of quaintness in both of these attitudes. We of the present are in the habit of acknowledging the autonomy of science, and the unimpeachable validity of the results of experimental research in so far as they are sanctioned by the consensus of experts. But at the same time we recognize the definiteness of the task of science, and the validity of such reservations as may be made from a higher critical point of view. Science is to be transcended in so far as it is understood as a whole. Philosophy is critically empirical; empirical, because it regards all _bona fide_ descriptions of experience as knowledge; critical, because attentive to the conditions of both general and special knowledge. And in terms of a critical empiricism so defined, it is one of the problems of philosophy _to define and appraise the generating problem of science_, and so to determine the value assignable to natural laws in the whole system of knowledge. [Sidenote: The Spheres of Philosophy and Science.]