All parts of the world must eventually decay. I should say 'change' to be more precise, but I'll use the common word so you understand me better. Now think about this: if this decay is both harmful and unavoidable, wouldn't the whole universe be in trouble? All its parts would be doomed to change, and the universe itself would be designed for corruption since it's made of different and opposing things.
All parts of the world, (all things I mean that are contained within the whole world), must of necessity at some time or other come to corruption. Alteration I should say, to speak truly and properly; but that I may be the better understood, I am content at this time to use that more common word. Now say I, if so be that this be both hurtful unto them, and yet unavoidable, would not, thinkest thou, the whole itself be in a sweet case, all the parts of it being subject to alteration, yea and by their making itself fitted for corruption, as consisting of things different and contrary?