XXII. (113) But some of those persons who have fancied that the world is everlasting, inventing a variety of new arguments, employ also such a system of reasoning as this to establish their point: they affirm that there are four principal manners in which corruption is brought about, addition, taking away, transposition, and alteration; accordingly, the number two is by the addition of the unit corrupted so as to become the number three, and no longer remains the number two; and the number four by the taking away of the unit is corrupted so as to become the number three; again, by transposition the letter Z becomes the letter H when the parallel lines which were previously horizontal (3/43/4) are placed perpendicularly (1/2 1/2), and when the line which did before pass upwards, so as to connect the two is now made horizontal, and still extended between them so as to join them. And by alteration the word oinos, wine, becomes oxos, vinegar. (114) But of the manner of corruption thus mentioned there is not one which is in the least degree whatever applicable to the world, since otherwise what could we say? Could we affirm that anything is added to the world so as to cause its destruction? But there is nothing whatever outside of the world which is not a portion of it as the whole, for everything is surrounded, and contained, and mastered by it. Again, can we say that anything is taken from the world so as to have that effect? In the first place that which would be taken away would again be a world of smaller dimensions than the existing one, and in the second place it is impossible that any body could be separated from the composite fabric of the whole world so as to be completely dispersed. (115) Again, are we to say that the constituent parts of the world are transposed? But at all events they remain in their original positions without any change of place, for never at any time shall the whole earth be raised up above the water, nor the water above the air, nor the air above the fire. But those things which are by nature heavy, namely the earth and the water, will have the middle place, the earth supporting everything like a solid foundation, and the water being above it; and the air and the fire, which are by nature light, will have the higher position, but not equally, for the air is the vehicle of the fire; and that which is carried by anything is of necessity above that which carries it. (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.