been conjoined with the presence of the cause, so it has no possibility by virtue of its essence while it exists.

Accordingly, describing it as possible while its existence is necessary is untenable. Thus, dividing necessary existence into necessary and possible in this sense is invalid. This differs from the division made by those who divide existence into necessary and possible, defining the possible as that which is described as existent at one time and nonexistent at another, so that it sometimes exists and sometimes does not. Dividing existence into necessary and possible in this sense involves no contradiction: it is described as possible when nonexistent because it can exist, and it is described as possible when existent because its existence was possible, just as its nonexistence was possible.

[The eighth argument]

As for someone who says, “It has possibility by virtue of its essence,” or, “Its essence admits existence and nonexistence,” or something similar, he should be asked: Is this essence, insofar as it is an essence, and leaving aside its existence—as you have supposed—necessary, possible, or impossible? If it is necessary or impossible, then it cannot be possible. If it is possible, it cannot be an essence unless something else makes it an essence, just as it cannot exist unless something else makes it exist. Indeed, by the logic of what they have stated, its being an essence cannot be established except through a cause