If then God created the male and female out of one, to this end that they should be one, why then henceforth were not they born man and wife at one birth, as it is with certain insects? Because God created male and female for the continuance of the species, yet is He ever a lover of chastity, and promoter of continence. Therefore did He not follow this pattern in all kinds, to the end that, if any man choose to marry, he may know what is, according to the first disposition of the creation, the condition of man and wife; but if he choose not to marry, he shall not be under necessity to marry by the circumstances of his birth, lest he should by his continence be the destruction of the other who was not willing to be continent; for which same cause God forbids that after being joined in wedlock one should separate if the other be unwilling.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).