Chapter 23 [X.]—The Pelagians Affirm that God in the Case of Abraham and Sarah Aroused Concupiscence as a Gift from Heaven.
He has much also to say, though to no purpose, concerning Abraham and Sarah, how they received a son according to the promise; and at last he mentions the word concupiscence. But he does not add the usual phrase, “of the flesh,” because this is the very thing which causes the shame. Whereas, on account of concupiscence there is sometimes a call for boasting, inasmuch as there is a concupiscence of the spirit against the flesh, and a concupiscence of wisdom. Accordingly, he says: “Now you have certainly defined as naturally evil this concupiscence which is indispensable for fecundity; whence comes it, therefore, that it is aroused in aged men by the gift of Heaven? Make it clear then, if you can, that that belongs to the devil’s work, which you see is conferred by God as a gift.” He says this, just as if concupiscence of the flesh had been previously wanting in them, and as if God had bestowed it upon them. No doubt it was inherent in this body of death; that fecundity, however, was wanting of which God is the author; and this was actually given whensoever God willed to confer the gift. Be it, however, far from us to affirm, what he thought we meant to say, that Isaac was begotten without the heat of sexual union.
Reproduced in full. Translation: Nicene and Post-Nicene Fathers, series 1, vol. 5 (Schaff, 1887), public domain (Public domain).