By the same reason, if all the elements are mutable, every body is mutable.
Now, according to your doctrine, all the elements are mutable; all bodies, therefore, are mutable.

But if there were any body immortal, then all bodies would not be mutable.

Every body, then, is mortal; for every body is either water, air, fire, or earth, or composed of the four elements together, or of some of them.

Now, there is not one of all these elements that does not perish; for earthly bodies are fragile: water is so soft that the least shock will separate its parts, and fire and air yield to the least impulse, and are subject to dissolution; besides, any of these elements perish when converted into another nature, as when water is formed from earth, the air from water, and the sky from air, and when they change in the same manner back again.

Therefore, if there is nothing but what is perishable in the composition of all animals, there is no animal eternal.
XIII.