[238] For, as the earth is the most appropriate place for land animals, and above all for reptiles, which do not endure even to crawl upon it, but seek caves and lurking places, avoiding the regions which are above, on account of their kindred with the things which are below; so, in the same manner, the air is the appropriate abode for the winged race, the element which is by nature light is the proper home for those creatures which are light by reason of their being feathered. When, therefore, those creatures, whose nature it is to traverse the air and who ought to roam through the aether, descend and come down upon the land, they are unable to live a life according to their nature.