Now, the spontaneous upsettings of brains this way and that at particular moments into particular ideas and combinations are matched by their equally spontaneous permanent tiltings or saggings towards determinate directions. The humorous bent is quite characteristic; the sentimental one equally so. And the personal tone of each mind, which makes it more alive to certain classes of experience than others, more attentive to certain impressions, more open to certain reasons, is equally the result of that invisible and unimaginable play of the forces of growth within the nervous system which, irresponsibly to the {251} environment, makes the brain peculiarly apt to function in a certain way. Here again the selection goes on. The products of the mind with the determined aesthetic bent please or displease the community. We adopt Wordsworth, and grow unsentimental and serene. We are fascinated by Schopenhauer, and learn from him the true luxury of woe. The adopted bent becomes a ferment in the community, and alters its tone. The alteration may be a benefit or a misfortune, for it is (_pace_ Mr. Allen) a differentiation from within, which has to run the gauntlet of the larger environment's selective power. Civilized Languedoc, taking the tone of its scholars, poets, princes, and theologians, fell a prey to its rude Catholic environment in the Albigensian crusade. France in 1792, taking the tone of its St. Justs and Marats, plunged into its long career of unstable outward relations. Prussia in 1806, taking the tone of its Humboldts and its Steins, proved itself in the most signal way 'adjusted' to its environment in 1872. Mr. Spencer, in one of the strangest chapters of his Psychology,[17] tries to show the necessary order in which the development of conceptions in the human race occurs. No abstract conception can be developed, according to him, until the outward experiences have reached a certain degree of heterogeneity, definiteness, coherence, and so forth.