Omens (as has been mentioned) resemble warnings: (_a_) Like warnings, they precede events, but do not cause them. (_b_) They sometimes precede an event by a considerable interval, as if to give time for precaution. (_c_) They do not announce the details of any event (which a friendly counsellor may not know), but only its character as good or evil. Then, if they are warnings (implying foreknowledge), since they are not the act of any man, they must be given by some spirit or other intelligence. So that once a belief in the intervention of spirits in mundane affairs has become prevalent in any tribe, nothing can be more natural than to regard Omens as spiritual messages. Still, this way of thinking may have been preceded by a disposition to attribute Omens to the good will of animals, especially Totems; for animals are often wiser than we are. In Australia the Turbal tribe held that the chirping of insects foretold the coming of blacks; a Wakelbwa who dreamed of a kangaroo would expect one of the Banbe subclass next day; to dream of old-man kangaroos sitting round the fire presaged danger.[355] Among the Yuin (Western Australia) a Black-Duck clansman thought that black ducks warned him against enemies; and men of the Kurnai, who had personal Totems, thought they gave protection by warnings.[356] Very early, however, ghosts or spirits sometimes come themselves to instruct us; as amongst the Kurnai, the Biraark (wizards) hold _séances_ at night, when ghosts attend, and give news of enemies or of absent friends.[357] In New Guinea, the ghosts of dead tribesmen send their surviving relatives Omens by fishes or birds.[358] By this animistic theory Omens are intimately connected with Oracles and Dreams; for these, too, are messages from the spirit-world. Dreams are the chief causes of belief in spirits, and with many people have not yet lost the character of supernatural visitations. Probably for ages past there have been in each generation a few rationalists, who treated dreams in the manner of Artabanes (as reported by Herodotus[359]—who, however, will show that the event refuted him), holding that “whatever a man has been thinking of during the day is wont to hover round him in the visions of his dreams at night.” Incensed against the diviners, rationalists have, in fact, too much despised and neglected dreams.