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290 does not, any more than the lesser ones, spread itself through the packed community, but is strictly isolated. How strange this seems! A parliament (though I heard no nonsense talked) of lively, eminently gregarious birds, all of which are noisy at one time or another, and from the thick of them a storm of clamour bursts: would not one think that the birds sitting cheek by jowl with the stormers would storm too, and so 'pass it on'? Why should there be a periphery, and what should limit the chorus except the bound of the plantation itself? Do crowds shout in patches? That the clamour should cease, after a time, is, of course, natural, but why, though it died along the road by which it travelled, should it not keep travelling on, through all the black, serried ranks? If rooks were influenced only by the outward manifestations of each other's emotions, one might, surely, expect this. But now, if they were influenced more by the thought itself, rapidly transmitted from one to another of them, then, whenever this factor ceased, for whatever reason, to act, the birds beyond the limits of its action might be unaffected by the cries of those who had felt its influence, for they would have been accustomed to look for a sign from within, and not from without. They might then hear, on some occasions, without being impelled, though on other occasions they might choose, to join. It may be difficult to realise such a psychical state, but that does not, of itself, make the state impossible. Its possibility would depend upon the reality or not of collective thinking, or thought-transference, and observation is (or should be) our only means of deciding as to this.