row, the habits necessary for successful struggle for life run in few lines, and these lines become deepened with every generation, until they become, as it were, petrified in brain-structure.
Instinct, therefore, is accumulated experience, or knowledge of many generations fixed permanently and petrified in brain-structure. All such petrifaction arrests development, because unadaptable to new conditions. They are found, therefore, only in classes and families widely differentiated from the main stem of evolution, from the lowest animals to man. Instincts are, indeed, the flower and fruit at the end of these widely-differentiated branches, but flowering and fruiting arrest onward growth.
Now, there is also a social evolution. The organic evolution, which found its term in man, is continued by man in social evolution. It is natural, therefore, to look for the corresponding phenomenon in the higher sphere of social evolution. I believe we find it in the phenomenon of arrested civilizations, of which nearly all barbarous and semi-civilized races are examples, but the Chinese and Japanese are the most conspicuous; and also, perhaps, to some extent, in the phenomenon of dead civilizations, of which the Greek and Roman are the most conspicuous. Nations isolated and breeding true, i. e., without mixture with other nations, gradually assume fixed customs and habits which become enforced, and therefore perpetuated by law, and finally petrified in national character. The result is often marvelous development, but extremely limited. Here, again, perfect flower and fruit destroy growth. Here again, also, it occurs in a type or branch widely differentiated from the main stem of social progress. This explains one of the advantages of cross-breeding, or mixing of varieties within certain limits of national varieties, if not of races.[1] It confers plasticity; it prevents the formation of fixed national character, and the consequent arrest of progress by petrifaction.
Let us hope, then, that the growing tree of society will always remain an excurrent; that its upshooting stem shall never lose itself in mere branches; that its terminal bud shall never fail, but always continue to grow. Its branches may flower, and fruit, and die, or cease to grow, but the trunk stretches ever upward and bears each successive flowering branch higher and still higher. Doubtless the ideal of humanity is that all right actions are spontaneously or instinctively performed, and all important truths intuitively or instinctively known; but this is and must be an unattainable ideal; for, this condition reached, how shall we any longer aspire?—the terminal bud flowering, how shall the tree continue to grow? Human nature must never petrify into instinct; inherited wealth must never supersede the necessity of individual acquirement.
- ↑ The effect of mixing varieties requires careful investigation, for it is yet very imperfectly understood. There seems little doubt, however, that there is a limit beyond which varieties do not mix with improvement.
