To secure these advantages of homogeneity, it is evident that the members of the herd must possess sensitiveness to the behaviour of their fellows. The individual isolated will be of no meaning, the individual as part of the herd will be capable of transmitting the most potent impulses. Each member of the flock tending to follow its neighbour and in turn to be followed, each is in some sense capable of leadership; but no lead will be followed that departs widely from normal behaviour. A lead will be followed only from its resemblance to the normal. If the leader go so far ahead as definitely to cease to be in the herd, he will necessarily be ignored.
The original in conduct, that is to say resistiveness to the voice of the herd, will be suppressed {30} by natural selection; the wolf which does not follow the impulses of the herd will be starved; the sheep which does not respond to the flock will be eaten.
Again, not only will the individual be responsive to impulses coming from the herd, but he will treat the herd as his normal environment. The impulse to be in and always to remain with the herd will have the strongest instinctive weight. Anything which tends to separate him from his fellows, as soon as it becomes perceptible as such, will be strongly resisted.
So far, we have regarded the gregarious animal objectively. We have seen that he behaves as if the herd were the only environment in which he can live, that he is especially sensitive to impulses coming from the herd, and quite differently affected by the behaviour of animals not in the herd. Let us now try to estimate the mental aspects of these impulses. Suppose a species in possession of precisely the instinctive endowments which we have been considering, to be also self-conscious, and let us ask what will