Fourth reply:
We say: When it is asserted, “This thing resembles that thing in such-and-such respect; therefore the ruling for one must match the ruling for the other in that respect,” nothing obliges us to extend that ruling beyond the specified respect. Blackness, for instance, shares with whiteness the fact that each is an accident subsisting in something else, yet blackness is not thereby required to share in being white. Likewise, a self-subsistent body shares with an accident the sheer fact of existence, but it need not share the distinctive properties that belong to accidents.

In the same way, if we hold—as is the sounder of the two opinions—that bodies are not identical, then when one body shares with another those properties that necessarily follow from corporeality, it is under no obligation to share what is peculiar to either of them. Thus, if the two agree in being objects that can be pointed to, or in being self-subsistent, or in possessing three dimensions, and the like, that does not compel earth to be identical to fire in what is unique to each, nor an apple to be identical to bread in what is unique to each of them.

This exposes the flaw in the argument. For when he said, “If you attribute your Originator to something that is designated by the same word you use for His creation—whether by spoken utterance or a mental act—and the thing so designated is neither originator, nor creator, nor fashioner, then it becomes possible that your Originator and Fashioner, in the respect you identified, resembles His creation, which you yourselves deny to be a creator or maker, namely that it is neither originator nor creator,” we reply: Your statement, “in the respect you identified, He resembles His creation”—do you mean by this that the very same property affirmed of Him is affirmed for the creature, such that whatever is possible for Him would likewise be possible for it