of a cause external to it. This is what they mean when they speak without qualification of something contingent in itself that needs an external cause: what is contingent in itself does not exist through itself; that is, it admits of nonexistence in itself.

This does not hold when some of its parts are necessary, for then only part of it admits of nonexistence, [not] the whole of it. Your error—or your attempt to show them to be in error—thus arises from the ambiguity of the expression “contingent in itself.”

Objections to rational proofs must address their substance. If you raised this as a verbal objection, it was of little benefit; if it was a substantive objection, it was inherently invalid.

When these thinkers said:

“An existing being is either necessary in itself or contingent in itself,”

they confined existence to these two categories—that is, they placed each individual existing being within one or the other. As for the aggregate encompassing both, it comprises both categories.

By “contingent” in the latter category, they mean that every constituent exists only through something separate from it. By “necessary in itself,” they mean that which does not depend in any respect on anything distinct from it.

It is evident that the former depends on a determining cause external to it, and that the aggregate of those contingent beings is itself contingent, depending on something that itself depends on a determining cause distinct from it.

Whatever depends on something that is itself dependent and distinct from it is all the more dependent on something distinct from it. As for