The Opinion of _Parmenides_, an ancient _Greek_ Author, appears in the following Lines, translated by _Cælius Siciensis_, from his Book which he wrote of Nature, concerning Hermaphrodites being produced[56]. ‘When the Semina of a Man and Woman are mixed together, the forming Virtue, preserving a due Moderation and Temperature, will produce Bodies properly made; for if there be an Opposition of the said Virtue in the mingled Semen, she unhappily implants in the Fœtus a double Sex.’ Here is the _Vis Informans_ accused of Opposition or Neglect in resisting, or letting the Semina go on their own way in the Formation of the Fœtus, which is much the same with _Constant_. _Africanus_’s Accusation of Forgetfulness or Impediment; and therefore what is said under that Author, will suffice for the rendering this Opinion also of little Worth. The Principles laid down by _Averroës_[57] are no less particular than others just mentioned; he says, The Semen Muliebre abounds with, or is constituted of, Particles adapted to the Nature of every Member in the Body, and in order to account for a Superfluity of Members in a Body, he draws this Conclusion from thence; that if the seminal Matter in a Female is more than is necessary for the Formation of one Child, and less than will make two, the superfluous Part will form superfluous Limbs to the one Child, according to the Nature of the Particles it contains; that is, if it consists of Particles fit for the Head, there will be two Heads, and so of the Hands, Feet, _&c._ and then he adds[58], ‘The Cause is much the same, when the Parts of Generation of both Sexes exist in any Person.’ And that on the other Hand, if their be a Deficiency of the seminal Matter, some Limb or other must be wanting. If this be thought a just Hypothesis, then we cannot but suppose, there is a great and most miserable Restraint upon the whole animal Part of the Creation; for if it be absolutely necessary that such a certain Quantity (and no more, nor less) is to be expended on the compleating of a proportionable Fœtus, I am of Opinion that not one third of the Animals of the World would escape being Monsters; and the Art and Business of Physicians would be more requisitely employed in ordering Regimens, and Calculations towards the fixing the Sustenance and other Non-naturals, in such Proportion to every Animal, as should produce in each an exact limited Quantity of seminal Matter, than in curing Diseases. But besides adjusting the necessary Quantity of such seminal Matter, it would be no less difficult to calculate a Proportion of Particles for each Part, since our Author makes some Head-Particles, some for the Feet, and so of the rest; least, tho’ the Quantity in the whole may be just enough, yet, the Head Particles, for example, might be too many, when there might at the same time be less of any other Part; so that according to this Notion, a Child might be begotten with a Head and half, and but half a Foot.