[154] At all events, if the Creator, employing that act by which he created amphibious animals, had chosen also by the same act to create a new animal, one capable of living in any element, then, this animal, if it forsook the weighty elements of earth and water, would necessarily have gone to those which are naturally light, namely, air and fire. And, on the other hand, supposing that it had originally dwelt among those elements whose place is on high, if it had sought to effect a migration from them, it would have changed to the opposite region; for it was at all events necessary for it to appear steadily in one portion of the world, since it was not possible for it to run away out of every element: since, in order that nothing external might be omitted, the Creator scattered the whole of the four principles of everything over the universe, in order to create the existing condition of the world, in order to make a most perfect universe of perfect parts.