John Cassian, Conferences I–X VIII.20: A question about the fallen angels who are said in Genesis to have had intercourse with the daughters of men

A question about the fallen angels who are said in Genesis to have had intercourse with the daughters of men.

Germanus: Since a passage of Genesis was a little while ago by the providence of God brought forward in our midst, and happily reminded us that we can now conveniently ask about a point which we have always longed to learn, we want to know what view we ought to take about those fallen angels who are said to have had intercourse with the daughters of men, and whether such a thing can literally take place with a spiritual nature. And also with regard to this passage of the gospel which you quoted of the devil a little while back, “for he is a liar and his father,” we should like in the same way to hear who is to be understood by “his father.”