The Natural Cause of Generation of Monsters, according to the Ancients, is either in the Matter, or in the Agent; in the Seed or in the Womb:  The Matter may be unable to perform its Office two ways; by Defect, or by Excess:  By Defect, when a Child hath but one Arm, or one Leg, &c. and by Excess, when it hath three Hands or two Heads.  The Agent or Womb may be in Fault several ways, as in the forming Faculty, which may be too strong or too weak, by which a deprav’d Figure is oftentimes produc’d, the ill Conformation of the place of Conception will cause a Monstrous Birth; and the imaginative Power at the time of Conception, is so forcible, that it stamps a Character of the thing upon the Child; so that the Child of an Adulteress, by the strength of Imagination may have a nearer resemblance of her Husband, than of the Person who begat it.  And some Histories mention, that through this Imaginative Faculty, a Woman at the time of Conception, beholding the Picture of a Blackamoor, produc’d a Child resembling an AEthiopian.

Monsters are sometimes Engender’d by unseasonable amorous Embraces, as when a Man enters on the Pleasures of Venus at a time as the monthly Flowings are upon his Wife; For this being against Nature, it is no wonder that it should produce an unnatural Offspring.  If therefore a Man’s desire be never so great for Copulation at such a time, yet the Woman ought not to admit of his Embraces; the issue of those unclean Embraces proving often Monstrous, or dull and heavy, and Defective in their Understandings.

Sometimes by a corruption of Seed, Monstrous Shapes are form’d, which by some is ascrib’d to the bad Influence of the Planets, that were predominant at the time of Conception; and sometimes the straightness of the Womb is attended with many Inconveniencies, for Nature not having sufficient room to frame her Work in, the Child is rumpled up, which occasions some to have hump’d Backs, crooked Arms, and Legs, round Shoulders, Wry Necks, and the like.

The divine Cause of these Monstrous Generations, proceeds from the permissive Will of our Great Creator, who many times suffers Parents to bring forth such Deform’d Creatures as a Punishment for their Lust:  And some Authors are of Opinion, that outward deformity of Body is generally a Sign of the Pollution of the Heart, as a Curse upon the Child for the Incontinency of the Parents.

In the Writings of some Authors mention is made of Monsters engender’d by infernal Spirits; and as the Scriptures give us to understand that the Angels being taken with the Beauty of the Daughters of Men, went in unto them, and that from such a Conjunction, Giants were Born, so we may infer that if Angels can mix Amorously with Women, and engender Children, the Devils who only differ from Angels by their Fall, may also draw Women into immodest Pleasures, and Defile them with their Embraces:  But it is highly inconsistent to suppose that our Creator who is all Purity, would permit the worst of Spirits to propogate his diabolical Offspring.