John Locke. Treatise on Government. Chapter 7. Of Political or Civil Society. Section 78.
Conjugal society is made by a voluntary compact between man and woman; and tho' it consist chiefly in such a communion and right in one another's bodies as is necessary to its chief end, procreation; yet it draws with it mutual support and assistance, and a communion of interests too, as necessary not only to unite their care and affection, but also necessary to their common off-spring, who have a right to be nourished, and maintained by them, till they are able to provide for themselves.