In his defense of the Christian faith in the wake of pagan criticism, Bishop Augustine of Hippo (354–430) left no stone unturned in his magisterial treatise Concerning the City of God Against the Pagans (see this page). The question of the capability of angels and other aerial spirits to interact with human women by touch clearly vexed him, however, because his primary authorities for religious truth—the Hebrew and Christian scriptures—were elusive on this issue. While Augustine had to concede that examples of physical contact between angels and humans were known from the Bible, most notably the story of the Nephilim (see this page), he turned to pagan traditions to cast light on this dark corner of religious history. His equivocation on this issue gave Christian authors from the later Middle Ages license to pursue the topic further and thereby inflect it with their own concerns.
In the third book of this work we mentioned in passing the question whether angels, being spirits, could have physical connection with women, and we left the answer unresolved.[2] Now Scripture says, “He makes spirits his angels,” that is, those who are by nature spirits he makes into his angels, by imposing on them the duty of carrying messages.[3] For the Greek angelos, which becomes angelus in the Latin derivative, means nuntius, a “messenger,” in the Latin language…
Nevertheless it is the testimony of Scripture (which tells us nothing but the truth) that angels appeared to men in bodies of such a kind that they could not only be seen but also touched.[4] Besides this, it is widely reported that Silvani and Pans, commonly called incubi, have often behaved improperly towards women, lusting after them and achieving intercourse with them.[5] These reports are confirmed by many people, either from their own experience or from the accounts of the experience of others, whose reliability there is no occasion to doubt. Then there is the story that certain demons, whom the Gauls call Dusii, constantly and successfully attempt this indecency. This is asserted by so many witnesses of such a character that it would seem an impertinence to deny it. Hence I would not venture a conclusive statement on the question whether some spirits with bodies of air (an element which even when set in motion by a fan is felt by the bodily sense of touch) can also experience this lust and so can mate, in whatever way it can, with women, who feel their embraces.