In a marriage, however, even when there have been contractual elements, the point of the marriage was to do something more than a contract could do. We might say that the marriage relationship was covenantal because it made it possible for the married couple to do something that they could not do merely as individuals.

What that something-more was might be easily specifiable: we enter into this marriage in order to produce an heir. However, it also might not be specified so easily. It includes matters such as the creation of (ideally) stable relations in which to raise children, or the natural foundation for all ethical and political life (as in Aristotle).

Those things are true of marriage, but they tell us about its necessity or its results and don't get directly at its essence. For that, the 19th-century German thinker, G. W. F. Hegel, gets most closely to the truth of things when he says:

Marriage is essentially an ethical relationship. Formerly, especially in most treatments of natural right, attention was paid only to the physical side of marriage or to its natural character. Consequently, it was treated as only a sexual relationship . . . . It is equally crude to think of marriage as only a civil contract . . . . On such a view, the individual humans are bound by a contract of mutual wilfulness, and marriage is degraded to the level of a contract for reciprocal use. A third notion posits marriage in love alone, but this too must be rejected, because love is only a feeling and so is exposed in every respect to contingency, a shape ethicality may not assume. Marriage, therefore, is determined more precisely as rightful, ethical love . . . . The ethical aspect of marriage consists in the parties' consciousness of this union as their substantial aim, and thus in their love, trust, and common sharing of their entire worldly being. (Philosophy of Right ¶¶ 161, 173)

Hegel is right: marriage is not just about sex, nor is it merely a civil contract, nor is it merely about love—though none of those three is irrelevant to it. Marriage is an ethical relationship in which the unity of that relationship is paramount and the couple is explicitly aware of its importance.

As Hegel says, in marriage a couple shares their "entire worldly being." A married couple is a new thing, an individual with two hearts and two minds and yet, nevertheless, an individual in the root sense of that word, a living being that cannot be divided without killing it.