ST Suppl., q. 41
Of the Sacrament of Matrimony as Directed to an Office of Nature
Supplement — compiled posthumously from Aquinas's early Sentences commentary
In the next place we must consider matrimony. We must treat of it (1) as directed to an office of nature; (2) as a sacrament; (3) as considered absolutely and in itself. Under the first head there are four points of inquiry:
(1) Whether it is of natural law?
(2) Whether it is a matter of precept?
(3) Whether its act is lawful?
(4) Whether its act can be meritorious?