Incubi and Succubi: Demonologists and Theologists on the Existence and Nature of Sexual Demons Sexual Demons
City of God
There is, too, a very general rumor, which many have verified by their own experience, or which trustworthy persons who have heard the experience of others corroborate, that sylvans and fauns, who are commonly called ‘incubi,’ had often made wicked assaults upon women, and satisfied their lust upon them; and that certain devils, called Duses by the Gauls, are constantly attempting and effecting this impurity is so generally affirmed, that it were impudent to deny it.
St. Augustine, The City of God, Book XV, Chapter 23
Summa Theologia
Still if some are occasionally begotten from demons, it is not from the seed of such demons, nor from their assumed bodies, but from the seed of men taken for the purpose; as when the demon assumes first the form of a woman, and afterwards of a man; just as they take the seed of other things for other generating purposes, as Augustine says (De Trin. iii), so that the person born is not the child of a demon, but of a man.
St. Thomas Aquinas, Summa Theologia, Part I, Question 51, Article 3
Demoniality, or Incubi and Succubi
...the children thus begotten by Incubi are tall, very hardy and bold, very proud and wicked. Thus writes Maluenda; as for the cause, he gives it from Vallesius, Archphysician in Reggio: “What Incubi introduce into the womb, is not any ordinary human semen in normal quantity, but abundant, very thick, very warm, rich in spirits and free from serosity [wateriness]. This, moreover, is an easy thing for them, since they merely have to choose ardent, robust men, whose semen is naturally very copious, and with whom the Succubus has connection, and then women of a like constitution, with whom the incubus copulates, taking care that both shall enjoy a more than normal orgasm, for the more abundant is the semen the greater the venereal excitement.” Those are the words of Vallesius, confirmed by Maluenda who shows, from the testimony of various Authors, mostly classical, that such associations gave birth to: Romulus and Remus, according to Livy and Plutarch... Plato the Philosopher, according to Diogenes Laertius and Saint Hieronymus; Alexander the Great, according to Plutarch and Quintus-Curtius... the emperor Cæsar Augustus, according to Suetonius... as also Merlin or Melchin the Englishman, born from an Incubus and a nun, the daughter of Charlemagne...
Father Ludovicus Maria Sinistrari de Ameno, Demoniality, or Incubi and Succubi
The Malleus Maleficarum
Whether children can be generated by Incubi and Succubi.
But it may be argued that devils take their part in this generation not as the essential cause, but as a secondary and artificial cause, since they busy themselves by interfering with the process of normal copulation and conception, by obtaining human semen, and themselves transferring it....
Therefore bodies which are assumed in this way cannot either beget or bear.
Yet it may be said that these devils assume a body not in order that they may bestow life upon it, but that they may by the means of this body preserve human semen, and pass the semen on to another body....
Secondly, it is true that to procreate a man is the act of a living body. But when it is said that devils cannot give life, because that flows formally from the soul, it is true; but materially life springs from the semen, and an Incubus devil can, with God's permission, accomplish this by coition. And the semen does not so much spring from him, as it is another man's semen received by him for this purpose (see S. Thomas, I. 51, art. 3). For the devil is Succubus to a man, and becomes Incubus to a woman. In just the same way they absorb the seeds of other things for the generating of various thing, as S. Augustine says, de Trinitate 3.
