From the beginning, God had implanted in the heart of man the precepts of the natural law. Then he was content to remind him of them. This was the Decalogue. 31
Catechism number 2071
The commandments of the Decalogue, although accessible to reason alone, have been revealed. To
attain a complete and certain understanding of the requirements of the natural law, sinful humanity needed
this revelation:
We know God's commandments through the
divine revelation proposed to us in the Church, and through the voice of moral conscience. the obligation
of the Decalogue