Those of us who had classical education and Catholic education at its best, know about natural law. So did the ancients, such as Aristotle and Cicero.
The Lord in His Wisdom gave us Revelation through the Jews and the study of Reason from the Greeks, such as Socrates, Aristotle and Plato. As thinking beings, humans have been given from God the ability to reason, to choose, to act in human ways.
Father Ripperger points out that in a depraved world, insanity becomes the norm, as sin leads to insanity. What the ancients discovered through reflection and what the Jews learned from God directly is that to be human is to act from a natural set of rules, which exist in the soul, simply because we are human. In fact, the Ten Commandments are "the" set of natural laws forgotten by men because of Original Sin.
Original Sin dulled man's ability to reason, "clouded the intellect" as all sin does. But, for the past fifty years of so, natural law philosophy has not been taught, even in Catholic universities, and most importantly, not in law schools.
I have taught Greek drama in the past and so much is based on natural law and the consequences of those who break it. We would not have the great tragedies of Oedipus or Antigone without the concept of natural law informing the dramas.
Our entire Catholic Faith presupposes that when God created man, He put His law in the heart, mind, soul of man and gave him the ability to reason. Nothing about the Old Testament, or the Act of Redemption by Christ makes sense without the concept that humans can now what is right and wrong. But, God knew post-Fall humans needed more than what was in their own souls and minds, which is why Moses was given the great commandments on stone. Men's hearts had grown cold to natural law and God had to intervene to remind men what was good, right, just.
That the Romans picked up the ideals of natural law made the philosophy "new" again for the world. Cicero was studied throughout the Middle Ages. Remember, that most, if not all the Doctors of the Church, such as Augustine and Bernard of Clairvaux, studied Cicero, in the context of God's plan for humanity to use reason to discover truth and goodness.
The great tragedy of modern education is that natural law philosophy and the concept of what it means to be a human, was purposefully suppressed by utilitarianism and the modernist heresies.
Without the classical studies of Western Civilization, re-discovered by so many home-schooling parents, students have been forced to try to understand morality, ethics, politics and social action without a framework.
to be continued