Against Celsus

But besides, if birds of augury converse with one another, as Celsus maintains they do, the prophetic birds having a divine nature, and the other rational animals also ideas of the divinity and foreknowledge of future events; and if they had communicated this knowledge to others, the sparrow mentioned in Homer would not have built her nest in the spot where a serpent was to devour her and her young ones, nor would the serpent in the writings of the same poet have failed to take precautions against being captured by the eagle. For this wonderful poet says, in his poem regarding the former:—

A mighty dragon shot, of dire portent;
From Jove himself the dreadful sign was sent.
Straight to the tree his sanguine spires he rolled,
And curled around in many a winding fold.
The topmost branch a mother-bird possessed;
Eight callow infants filled the mossy nest;
Herself the ninth: the serpent, as he hung,
Stretched his black jaws, and crashed the dying young;
While hovering near, with miserable moan,
The drooping mother wailed her children gone.
The mother last, as round the nest she flew,
Seized by the beating wing, the monster slew:
Nor long survived: to marble turned, he stands
A lasting prodigy on Aulis' sands.
Such was the will of Jove; and hence we dare
Trust in his omen, and support the war.

And regarding the second— the bird— the poet says:—

Jove's bird on sounding pinions beat the skies;
A bleeding serpent of enormous size,
His talons twined; alive, and curling round,
He stung the bird, whose throat received the wound.
Mad with the smart, he drops the fatal prey,
In airy circles wings his painful way,
Floats on the winds, and rends the heaven with cries;
Amidst the host, the fallen serpent lies.
They, pale with terror, mark its spires unrolled,
And Jove's portent with beating hearts behold.

Did the eagle, then, possess the power of divination, and the serpent (since this animal also is made use of by the augurs) not? But as this distinction can be easily refuted, cannot the assertion that both were capable of divination be refuted also? For if the serpent had possessed this knowledge, would not he have been on his guard against suffering what he did from the eagle? And innumerable other instances of a similar character may be found, to show that animals do not possess a prophetic soul, but that, according to the poet and the majority of mankind, it is the “Olympian himself who sent him to the light.” And it is with a symbolic meaning that Apollo employs the hawk as his messenger, for the hawk is called the “swift messenger of Apollo.”