One scarcely expects from a great poem, dealing with war and adventure, to gather information about birds. Yet it is there, but not so much scientific as ethical. Birds, they believed, were here on earth as the messengers of the gods. Rarely did a bird appear before them or raise a cry which did not do so by the direct command of some ruling divinity. Imagine with what anxiety these old Greek heroes watched for and listened to the heaven-sent messages. Great was the fear at certain omens, and great the rejoicing at others. As a rule only special men could interpret these signs and these men were of immense importance in a community. They were almost a priesthood in nature, as nearly so as any order which the people then possessed, for the priesthood was not developed at that time. In the Iliad, at four of the critical points in the story a bird appears and shows the will of the gods to mortals. It is related that before the Greeks sailed to Troy, while the ships were yet assembled at Aulis, one of these omens occurred and was interpreted thus: Near the ships was an altar and by the altar stood a plane-tree, upon the bough of which a little bird had built its nest, and already within the nest were nine fledglings. Suddenly a serpent darted forth from beneath the altar straight toward the tree; the nine little birds were soon devoured and at last the serpent ended his feast by catching the mother which had flown crying about it. At once the serpent was turned into stone. This wonderful prodigy was shown by one of the prophets to mean that for nine years the Greeks would toil fruitlessly before Troy as the serpent had devoured the nine little birds; but in the tenth year they would seize the city.