This is because what is contingent in itself is something that can exist or not exist. This is conceivable only of something that is nonexistent and can either come into existence or remain nonexistent.

As for something that has always existed through another, how can it be said that it can exist or not exist? Or that it admits of existence and nonexistence?

This becomes clearer when we consider whether that which admits of existence and nonexistence is the thing existing in external reality; or the essence existing in external reality, according to those who say that existence is additional to essence; or something that does not exist in external reality.

If the first alternative is maintained, it is impossible, because something that exists in external reality without beginning or end, being necessary through another, cannot admit of nonexistence at all. How, then, can it be said to admit of existence and nonexistence?

If something else is meant, then it has no reality capable of admitting existence or nonexistence, because the existence of each thing is identical with its essence in external reality. The mind, however, may conceive of an essence distinct from external existence. Thus, if essence is considered in the mind and existence in external reality, or