rising from the earth, then the earth has become wet; and if the earth has become wet, there has been rain; and if there has been rain, there have been clouds.

As for things that occur linearly, such as a human being coming from another human being, and that human being from yet another: if this is an essential causal relation, it cannot extend indefinitely, because if the first of the causes does not exist, the last does not exist. If, however, the relation is incidental—for example, if a human being is in fact brought into being by an agent other than a human being, namely God, who gives him his form, while the father’s role is merely that of a tool in relation to a craftsman—then, if that agent exists and acts endlessly through an infinite succession of changing instruments, there is nothing impossible in his continually producing human individuals through infinitely many individuals. I mean that he produces children through their fathers. This is alluded to in the words of the Most High:

“Be grateful to Me and to your parents.”

I say:

The import of this statement is that an infinite regress of causes is impossible, because the cause must exist when the effect exists.

As for conditions and effects—such as the case where