In attempting to illuminate the records of history by the principles of biology, an essential difficulty is the difference of scale in time upon which these two departments of knowledge work. Historical events are confined within a few thousands of years, the biological record covers many millions; it is scarcely to be expected, therefore, that even a gross movement on the cramped historical scale will be capable of detection in the vast gulf of time the biological series represents. A minor difficulty is the fact that the data of history come to us through a dense and reduplicated veil of human {101} interpretation, whereas the biological facts are comparatively free from this kind of obscuration. The former obstacle is undoubtedly serious. It is to be remarked, however, that there is strong reason to suppose that the process of organic evolution has not been and is not always infinitely slow and gradual. It is more than suspected that, perhaps as the result of slowly accumulated tendency or perhaps as the result of a sudden variation of structure or capacity, there have been periods of rapid change which might have been perceptible to direct observation. The infinitely long road still tending upwards comes to where it branches and meets another path, tending perhaps downwards or even upwards at a different slope. May not the meeting or branching form, as it were, a node in the infinite line, a resting place for the eye, a point in the vast extension capable of recognition by a finite mind and of expression in terms of human affairs? It is the belief of the writer that the human race stands at such a nodal point to-day. THE BIOLOGY OF GREGARIOUSNESS. In order to set forth the evidence on which is based the conclusion that the present juncture of affairs is not merely, as it very obviously is, a meeting-place of epochs in the historical series, but also marks a stage in the biological series which will prove to have been a moment of destiny in the evolution of the human species, it will be necessary to inquire somewhat closely into the biological meaning of the social habit in animals. In an earlier essay certain speculations in the same subject were indulged, and a certain amount of repetition will be necessary. The point of view then taken up, however, was different from that from which I shall now attempt to review the facts. Then the main {102} interest lay in an examination of the meaning of gregariousness for the individual mind, and although reasons enough were found for uneasiness at the course of events, and at the instability of civilization which any radical examination displayed, the inquiry was not pursued under any immediate imminence of disaster to the social fabric as it must be now. Naturally, therefore, at the present time certain aspects of the subject which before were of no special relevance become of great importance and demand close examination.