Since what shall we say? Must we not say that these animals which are terrestrial or aquatic live in air and spirit? What? Are not pestilential afflictions accustomed to exist when the air is tainted or corrupted, as if that were the cause of all such assuming vitality? Again, when the air is free from all taint and innocent, such as it is especially wont to be when the north wind prevails, does not the imbibing of a purer air tend to a more vigorous and more lasting duration of life?