Capítulo 15. Chapter XV.—Concerning Physical Change
[3.15.102] Some, too, maintain that what is called ‟physical change” is non-real, and the arguments they employ are such as these:[413] If a thing changes, what changes is either corporeal or incorporeal; but each of these is matter of dispute; therefore the theory of change will also be disputable.
[3.15.103] If a thing changes, it changes through certain actions of a Cause[414] and by being acted upon. But it does not change by being acted upon, for the reality of Cause is refuted, and therewith is refuted also the object which is acted upon, as it has no agent to act upon it.
[3.15.104] Therefore nothing changes at all. If a thing changes, either what is changes or what is not.[415] Now what is not is unreal and can neither act nor be acted upon at all, so that it does not admit of change either. And if what is changes, it changes either in so far as it is in being or in so far as it is not in being.
[3.15.105] Now in so far as it is not in being it does not change, for it is not even existent; while if it changes in so far as it is existent, it will be other than existent, which means that it will be non-existent. But it is absurd to say that the existent becomes non-existent; therefore the existent does not change either. And if neither the existent nor the non-existent changes, and besides these there is nothing else, it only remains to say that nothing changes.
[3.15.106] Some also argue thus:[416] That which changes must change in a certain time; but nothing changes either in the past or in the future, nor yet in the present, as we shall prove; nothing therefore changes. Nothing changes in the past or in the future, for neither of these times is present, and it is impossible to do or suffer anything in time that is not existent and present. Nor yet in time present.
[3.15.107] For the present time is probably also unreal,[417] and—even if we set aside this point—it is indivisible; and it is impossible to suppose that in an indivisible moment of time iron, say, changes from hard to soft, or any one of all the other changes takes place; for they appear to require extension in time. If, then, nothing changes either in the past or in the future or in the present, we must declare that nothing changes at all.
[3.15.108] Further, if change exists at all ⟨it is either sensible or intelligible; but it is not sensible, since the senses⟩ are specialized,[418] whereas change is thought to possess ‟concurrent recollection”[419] both of that from which it changes and that into which it is said to change. And if it is intelligible, then, since (as we have frequently pointed out already[420]) there exists among the ancients an unsettled controversy as to the reality of intelligibles, we shall also be unable to make any assertion about the reality of change.