T 3.2.12.3

Whoever considers the length and feebleness of human infancy, with the concern which both sexes naturally have for their offspring, will easily perceive, that there must be an union of male and female for the education of the young, and that this union must be of considerable duration. But in order to induce the men to impose on themselves this restraint, and undergo chearfully all the fatigues and expences, to which it subjects them, they must believe, that the children are their own, and that their natural instinct is not directed to a wrong object, when they give a loose to love and tenderness. Now if we examine the structure of the human body, we shall find, that this security is very difficult to be attain'd |on our part; and that since, in the copulation of the sexes, the principle of generation goes from the man to the woman, an error may easily take place on the side of the former, tho' it be utterly impossible with regard to the latter. From this trivial and anatomical observation is deriv'd that vast difference betwixt the education and duties of the two sexes.