The idea of the natural law comes from the ancient Greek philosophy where it was understood as predominantly static. Taken over into the Christian theology it was also understood as something stable, immoveable, unchangeable.
Many examples of this may be shown, including those from the Czech tradition of moral theology from the period prior to Vatican Council II. The present document represents a completely different approach: The natural moral law is something dynamic, connected with the human conscience, ways of self-realization and of estimating the good and evil.
It does not represent heteronomous control of conscience from outside but it is a principal orientation in which a person makes decisions with his or her own responsibility. The document is a proof of the ability of the church to react to the changes in the society, to develop her teaching and her self-understanding.