References in periodicals archive ?
That the semen cannot all be recovered after copulation is taken by them as evidence that the substance of the semen has been used up materially in the creation of the fetation.
It is not, as sometimes supposed, that he turns to these concepts because there is no other solution available to the aporia about the formation of the fetation by an internal or external agent.
Note that his first answer to this question depends on what he has already argued: that the fetation will be alive only on acquiring sentient soul, and this is what the male contributes.