IV. (14) But the Creator made two different races on the earth and in the air. In the air, he made the winged animals capable of being perceived by the external senses, and other powers which can by no means be comprehended in any place by the external senses; and this is the company of incorporeal souls arranged in order, but not in the same classifications. For it is said that some are assigned to mortal bodies, and are again subjected to a change of place according to certain defined periodical revolutions; but that others which have received a more divinely prepared habitation, look down upon the region of the earth, and that in the highest place, near the other itself, the purest souls are placed, which those who have studied philosophy among the Greeks call heroes, but which Moses, by a felicitous appellation, entitles angels; souls which go as ambassadors and messengers of good from the ruler of all things to his subjects, and messengers also to the king respecting those things of which his subjects have heard. To the earth again he assigned two classes, terrestrial animals and plants, wishing that she should be at the same time their mother and their nurse. (15) For, as in the case of woman and every animal of the female sex, fountains of milk spring up in them when they are about to bring forth, in order that they may supply the offspring that is born of them with necessary and suitable food; so in a similar manner God has assigned to the earth, which is the mother of all terrestrial animals, all the different species of plants, in order that the animals produced by the earth may have such food as is akin to them, and not alien from their natures. (16) And, indeed, God has caused plants to grow with their heads downwards, having fixed their heads in the deepest parts of the earth; and having drawn up the heads of the irrational animals from the earth, he has set them up high on long necks, putting their fore feet under their necks as a kind of foundation. (17) But man has received a pre-eminently superior formation. For of all other animals God has bent the eyes downwards, so that they look upon the ground; but on the other hand, he has raised the eyes of man so that he may behold the heaven, being not a terrestrial but a celestial plant as the old proverb Is.[this is similar to what Ovid says, which may be Translated�"and while all other creatures from their birth / With downcast eyes gaze on their kindred earth, / He bids man walk erect, and scan the heaven, / From whence he sprung, to which his hopes are given."]