Whether matrimony is of natural law?

❌ Objection 1 : It would seem that matrimony is not natural. Because "the natural law is what nature has taught all animals" [*Digest. I, i, de justitia et jure, 1]. But in other animals the sexes are united without matrimony. Therefore matrimony is not of natural law. Further, that which is of natural law is found in all men with regard to their every state. But matrimony was not in every state of man, for as Tully says (De Inv. Rhet.), "at the beginning men were savages and then no man knew his own children, nor was he bound by any marriage tie," wherein matrimony consists. Therefore it is not natural.

❌ Objection 2 : Further, natural things are the same among all. But matrimony is not in the same way among all, since its practice varies according to the various laws. Therefore it is not natural.

❌ Objection 3 : Further, those things without which the intention of nature can be maintained would seem not to be natural. But nature intends the preservation of the species by generation which is possible without matrimony, as in the case of fornicators. Therefore matrimony is not natural.