St. Isidore of Seville: Natural moral law

“Natural law is what is common to all peoples, and what is observed everywhere by the instinct of nature rather than by any ordinance, as the marriage of man and woman, the begetting and rearing of children, the common possession of all things, the one freedom of all, and the acquisition of those things that are taken in the air, or on land, or on sea. Likewise the restoring of property entrusted or lent, and the repelling of violence by force. For this, or anything like this, is not considered unjust but natural and fair.”

~St. Isidore of Seville (c. 560-636): Etymologies, 5, 4, 1-2.

St. Isidore of Seville 

by Bartolome Esteban Murillo. 

1665; Cathedral of Seville.

St. Isidore: "Natural law"

"NATURAL LAW is what is common to all peoples, and what is observed everywhere by the instinct of nature than by ordinance, as the marriage of man and woman, the begetting and rearing of children, the common possession of all things, the one freedom of all, and the acquisition of those things that are taken in the air, or on land, or on sea. Likewise the restoring of property entrusted or lent, and the repelling of violence by force. For this, or anything like this, is not considered unjust but natural and fair.”

~St. Isidore of Seville: Etymologies, 5, 5.

Page of Etymologiae, Carolingian manuscript (8th cent.),

Brussels, Royal Library of Belgium.

St. John Chrysostom: "The law which God ingrafted in man"

“WE use not only Scripture but also reason in arguing against the pagans. What is their argument? They say they have no law of conscience, and that there is no law implanted by God in nature. My answer is to question them about their laws concerning marriage, homicide, wills, injuries to others, enacted by their legislators. Perhaps the living have learned from their fathers, and their fathers from their fathers and so on. But go back to the first legislator! Was it not by his own conscience and conviction? Nor can it be said that they heard Moses and the prophets, for Gentiles could not hear them. It is evident that they derived their laws from the law which God ingrafted in man from the beginning.”

~St. John Chrysostom: Ad pop. Ant., XII, 4.

See also:
• Romans 2:12-15
• St. John Chrysostom: Homilies on the Epistle to the Romans, Homily V

Byzantine mosaic of St. John Chrysostom from the Hagia Sophia