Catechism of the Catholic Church §1978 — excerpt
The natural law is a participation in God's wisdom and goodness by man formed in the image of his Creator. It expresses the dignity of the human person and forms the basis of his fundamental rights and duties.
This translation is under copyright, so only the cited words are quoted here. Follow the link for the full text. Translation: English translation of the Catechism of the Catholic Church, 2nd ed. (Libreria Editrice Vaticana), as posted at vatican.va.