According to tradition, these "winged serpents" came into Egypt from Arabia at the commencement of spring. They always followed the same route, and invariably passed through a certain defile, where the Ibis waited for them and destroyed them. Herodotus adds that, having gone to Arabia to obtain some certain information about these "winged serpents," he saw, lying on the ground near the city of Buto, "an immense quantity of bones and vertebræ unmistakably those of the winged plagues." Since the time of Herodotus, a great many authors, probably on his authority, have reproduced this fable, and enriched it with variations more or less fanciful. Cicero, Pomponius Mela, Solinus, Ammianus, and Ælian have mentioned it. According to the last writer, the Ibis inspired the serpents with so much dread, that the very sight of its plumage was sufficient to drive them away, and a mere touch killed them at once, or at least stupefied them. Let it suffice that all these naturalists admit that the Egyptians venerated the Ibis for the service which it rendered by destroying numbers of venomous serpents. In the narrative of Herodotus, as we have seen, the expression "winged serpents" is used for venomous ones. The translation is rather a free one, it must be confessed. Moreover, it is the opinion of M. Bourlet, who has written a memoir on the subject, that by the term "winged serpents" Herodotus intended to describe locusts, innumerable swarms of which were wont to traverse Egypt and the adjacent countries, destroying everything as they pass. This explanation appears to us better than the former, for it is a fact that the Ibis cannot attack serpents, its bill being too weak for such a purpose. Having quoted M. Bourlet's opinion, we may as well give that of Savigny, the naturalist, whose studies on the subject have been published in the "Histoire Mythologique de l'Ibis." "Between aridity and contagion, the two scourges which in all ages have been so dreaded by the Egyptians," says the author, "it was soon perceived that when a district was rendered fertile and healthy by pure and fresh water, it was immediately frequented by the Ibis, so that the presence of the one always indicated that of the other, just as if the two were inseparable; they therefore believed that the two had a simultaneous existence, and fancied some supernatural and secret relations existed between them. This idea, being so intimately connected with the phenomena on which their existence depended--I mean the periodical overflowing of their river--was the first motive for their veneration of the Ibis, and became the basis of the homage which ultimately developed into the worship of the bird." Thus, according to Savigny, the Ibis was venerated by the Egyptians only because it announced to them the annual overflowing of the Nile. This explanation is now generally accepted.