For the wild man seeking game or on the alert for enemies it is necessary to read every sign of the presence of enemies or of game in the neighbourhood: footprints, broken twigs and bent grass, droppings of feathers, hair or dung, remnants of food or marks of habitation instantly catch his eye; noises or odours arrest his other senses. His world is full of these signs, and he must always be on the watch for them: the birds being suddenly silent, on looking up he sees a hawk; a change of wind, or the aspect of clouds, announces rain or fair weather; the coming and departure of certain birds—as with us the swallow and the cuckoo—portend the change of seasons. In all these cases causation is active and sometimes obvious, but often very obscure: the apparent may be the reverse of the real order: for the coming of swallows is the antecedent of our enjoying the summer; but in the order of nature the course of the seasons determines the migration of birds. That the true relation may be misunderstood is shown by the behaviour of certain Australian natives who, noticing that plovers cry before the coming of rain, take their cry to be a cause of rain, and therefore imitate it when performing their rain-rites.[342] We may observe how obscure is the distinction between sign and cause even amongst ourselves, in the general belief that “a change of the moon” is connected somehow with a change of weather; for what the relation is no one seems clearly to conceive. The relation between natural signs and the events signified, being obscure, may be mysterious; and accordingly its obscurity has been made use of to defend the belief in Omens. In the _De Divinatione_[343] Quintus, who is unkindly given by his brother the post of apologist for all that nonsense, (following, I suppose, the sophistry of some Stoic) quotes Aratus’ description of how certain movements of the sea presage a coming storm; the gull, too, and the crow by their behaviour: and the croaking of frogs and the snuffing of cattle foretell rain. I cannot explain, he says, how animals have such knowledge any more than I can explain the divinations of augurs; nor is it necessary to do so: in both cases there are the facts. No wonder, then, that the savage, depending for his life upon a knowledge of signs, driven by eagerness and anxiety to observe them, and unable to distinguish coincidence from causation and the entanglements of causation, should imagine himself to have discovered many more signs than are comprised in the order of nature. Thus in Torres Straits, the biro-biro announces by its arrival that yams are ready for eating (which seems needless), and the cry of the koko predicts fine weather (which is credible); but, further, the sunbird can foretell the coming of a boat,[344] and that must be imagination. § 3. SOME SIGNS CONCEIVED OF AS MAGICAL