To produce children is the object of marriage, though this object is sometimes frustrated. Among the different causes of sterility there are some alike common to men and women; but as in men they are more apparent, to men they are more commonly attributed. In both sexes, sterility is occasioned either by an inherent defect in the conformation of the organs, or by accidental injuries to the organs themselves. Among men, the most essential imperfections in the conformation are those which affect the testicles, or those parts called the _erectores penis_. The false direction of the urethra, which is sometimes not only oblique, but badly perforated, is another obstacle to generation; as is the adherence of the prepuce to the bridle, which may, however, be corrected. In women, the conformation of the matrix may likewise be imperfect; and the perpetual closure or expansion of the orifice of the matrix, are defects which are alike repugnant to generation. But the most frequent cause of sterility, both in men and women, is the corruption of the seminal liquid in the _testes_; for if the secretion, by which the semen be formed, is vitiated, the fluid must be incapable of impregnation; in which case, though the organs may have every appearance of being properly qualified for it, there will be no procreation; but these causes have no external appearance.
In cases of sterility, different means have been employed to discover whether the defect was to be imputed to the man or the woman. Of these, inspection is the chief; and indeed, if the sterility be occasioned by an external fault in the conformation, this is sufficient. But if the defect is in the internal organs, it is almost impossible to discover or remove it. There are men, to all appearance well formed, who want the genuine sign of a proper conformation; and others who have it in so slight a degree as to make the mark of virility extremely equivocal. This is the most animal part of the human frame, and is constantly under the influence of instinct, and not governed by that of the mind. Many young persons of the purest ideas have been subjected to the liveliest sensations, though ignorant of pleasure, or the cause, and others remain cold and languid notwithstanding the efforts of imagination.