[116] Once more: we must not imagine that the world is destroyed by alteration, for the change of any elements is equipollent, and that which is equipollent is the cause of unvarying steadiness, and of untroubled durability, inasmuch as it neither seeks any advantage itself, and is not subject to the inroads of other things which seek advantages at its expense; so that this retribution and compensation of these powers is equalized by the rules of proportion, being the produce of health and endless preservation, by all which considerations the world is demonstrated to be eternal.