and all of them are nonexistent in external reality—indeed, all of them are impossible in external reality. For if a contingent being is supposed to have no self-existent being to bring it into existence, it is impossible because of something else. Thus, if it is supposed that nothing exists externally except what has no existence of itself, then nothing exists externally except what is impossible to exist, either in itself or because of something else. The nonexistence of any such thing does not require a cause necessitating its nonexistence. Rather, it is nonexistent of itself, whether its existence is possible or impossible. In that case, there is nothing externally but continuing nonexistence.

If, after this, it is said, “That which has no existence of itself exists through this other thing which has no existence of itself, and so on,” this would be equivalent to saying, “This nonexistent thing exists through this other nonexistent thing, and so on.” Rather, of the nonexistent it is said, “This impossible being exists through this other impossible being.” This is a contradiction: you have made the nonexistent exist through something nonexistent and extended this into a regress. You have thus combined a regress of nonexistent things with making each one of them that which brought the other nonexistent thing into existence.

[Fourth]

It may be said: A contingent being does not come to exist merely through another contingent being, for the existence of that other contingent being does not prevail over its nonexistence except through something else. If the contingent being supposed to be the agent, the effective cause that makes existence prevail, has not itself had its existence prevail over its nonexistence, but admits both existence and nonexistence, then the contingent being supposed to be the effect—the thing acted upon and produced, whose existence is made to prevail—is all the more unlikely to have its existence prevail over its nonexistence; rather, it admits existence