But the movement towards harmony, the elimination of evil, will not be effected by idealists imposing their constructions upon the world or by authoritarian governments.  It means gradual adaptation, gradual psychological change, and its life is individual liberty.  It proceeds by the give and take of opposed opinions.  Guizot had said, “Progress, and at the same time resistance.”  And Spencer conceives that resistance is beneficial, so long as it comes from those who honestly think that the institutions they defend are really the best and the proposed innovations absolutely wrong.

It will be observed that Spencer’s doctrine of perfectibility rests on an entirely different basis from the doctrine of the eighteenth century.  It is one thing to deduce it from an abstract psychology which holds that human nature is unresistingly plastic in the hands of the legislator and the instructor.  It is another to argue that human nature is subject to the general law of change, and that the process by which it slowly but continuously tends to adapt itself more and more to the conditions of social life—­children inheriting the acquired aptitudes of their parents—­points to an ultimate harmony.  Here profitable legislation and education are auxiliary to the process of unconscious adaptation, and respond to the psychological changes in the community, changes which reveal themselves in public opinion.

3.

During the following ten years Spencer was investigating the general laws of evolution and planning his Synthetic Philosophy which was to explain the development of the universe. [Footnote:  In an article on “Progress:  its Law and Cause,” in the Westminster Review, April 1857, Spencer explained that social progress, rightly understood, is not the increase of material conveniences or widening freedom of action, but changes of structure in the social organism which entail such consequences, and proceeded to show that the growth of the individual organism and the growth of civilisation obey the same law of advance from homogeneity to heterogeneity of structure.  Here he used progress in a neutral sense; but recognising that a word is required which has no teleological implications (Autobiography, i. 500), he adopted evolution six months later in an article on “Transcendental Physiology” (National Review, Oct. 1857).  In his study of organic laws Spencer was indirectly influenced by the ideas of Schelling through von Baer.] He aimed at showing that laws of change are discoverable which control all phenomena alike, inorganic, biological, psychical, and social.  In the light of this hypothesis the actual progression of humanity is established as a necessary fact, a sequel of the general cosmic movement and governed by the same principles; and, if that progression is shown to involve increasing happiness, the theory of Progress is established.  The first section of the work, first principles, appeared in 1862.  The biology, the psychology,