Köln, Erzbischöfliche Diözesan- und Dombibliothek 127, fol. 9r-9v

Gratian, Decretum D.1 c.7

There is another type of law as Isidore says in his Etymologies

 What is natural law?

Natural law is common to all nations.  It has its origins in nature not in any constitution.  Examples of natural law are the union of men and women, the procreation and raising of children, the common possessions of all persons, the equal liberty of all persons, the acquisition of things that are taken  from the heavens, earth, or sea, the return of property or money that has been deposited or entrusted.  This also includes the right to repel violence with force.

 § 1. These things and similar are never unjust but are natural and equitable.