2. Every science, no doubt, is to some extent, the playground of analogies; but the complexity and the unmateriality of human relations has forced this character upon social theory in an extraordinary degree. It is impossible to account for the tendencies of sociological as well as of philosophical thought without making some attempt to pursue the line of investigation suggested by Mr. Bagehot in his _Physics and Politics_. Predominant modes and types of experience necessarily colour the whole activity of the mind, and, as indicated above, this influence more especially affects a province of research which is not _prima facie_ accessible to direct experiment or sensuous observation. I must, therefore, endeavour to review, in a brief outline, the principal branches of experience which have furnished ideas for application to social theory, and to indicate the leanings in speculation upon society, which have been due to preoccupation with one or another special analogy. i. The Newtonian theory of gravitation is the entrance gate to the modern world of science. {20} “When the Newton of this subject shall be seated in his place” [1] is the aspiration of the modern investigator in every matter capable of being known. It is not surprising, therefore, that the inclusion of human society within the range of matters capable of being definitely understood, should have been symbolized by demanding for social science a completeness of explanation and a power of prediction analogous to those displayed by astronomy or by mathematical physics. Representative of this conception is the title, Social Physics--for Comte the alternative and equivalent to the name Sociology. It is easy to see both the merits and the dangers of such an ideal, which, as the embodiment of perfection in a natural science, is presupposed by the attitude of sociology down to the present day. Is a science necessarily a natural science, and is a natural science necessarily an exact science?--these are the fundamental questions involved in the adoption of a mathematical ideal for the study of society. No fault can be found with it on the ground of its implying the highest degree of harmony and precision; the only question is whether an adequate type of comparison is afforded for, let us say, the growth of an institution, by the law of a curve. The general conception, indeed, of a continuity between human relations and the laws of the cosmic order is thoroughly in the spirit of Plato, and betokens a scientific enthusiasm worthy to be the parent of great things. And especially in the sphere of economic science, where certain relatively simple hypotheses have proved on the whole to be effective instruments {21} of explanation, an analysis of intricate phenomena has been effected, which in some degree justifies the aspiration after the ideal of an exact science. [1] De Morgan, _Budget of Paradoxes_, p. 355.