Human nature is designed to know the truth and desire the good.
I cannot chose absolute evil because it does not exist but I may use good creatures in ways destructive to good order and human destiny. A simple example will make this clear.

An apple is good in itself because it is a creature. It is also good for eating, but if I eat too many of them I will go beyond the limits of my stomach and harm myself.
Or, I may steal the apple thus disturbing the harmony with my fellow man. I can use the apple as a weapon to throw at those I don't like, thus again disturbing my relationship with my fellow man. I may even use an apple as a bribe so as to gain favor with my teacher.

So the dictate of reason tells me-
- to not overeat
- do not steal
- do not harm your fellow man
- do not bribe, all of these are dictates of reason or aspects of the Natural Law.

 

Long ago the Stoics realized that the universe was ruled by reason and that human being have the ability to reason and thus discover truth. Marcus Aurelius, the Stoic Roman emperor (121-180 AD) who believed that God and Nature were the same, stated the human predicament thus:

"Remember always that the World-Nature is, and what my own nature is, and how the one stands in respect to the other - so small a fraction to the vast Whole - bear in mind that no man can hinder you from comforming each word and deed to that Nature of which you are part." (Marcus Aurelius, Meditations, Penguin Books, 1964, p. 47)

Jonathan Dolherty, Ph. D. sums up Natural law as follows:

1. is not made up by human beings;
2. is based on the structure of reality itself;
3. is the same for all human beings and at all times
4. is an unchanging rule or pattern which is there for human beings to discover;
5. is the naturally knowable moral law;
6. is a means by which human beings can rationally guide themselves to their good.

"Man's infinite capacity to know and to love shows that he is destined to know and love and infinite being, God."

So, the order found in creatures point to the eternal order for the universe in God. St. Thomas points out that the eternal order in itself is only known by God and the blessed in heaven. Creatures in history know the eternal order by reflection, for every knowledge of the truth is a reflection and participation in God's eternal law which is an unchanging truth. (Summa: I, Q.93, Art. 2)

The 21st century man is prone toward relativism which means that he tends not recognize absolute moral truth. Pope John Paul II has well noted: "The saving power of truth is contested, and freedom alone, uprooted from any objectivity, is left to decide by itself what is good and what is evil". (John Paul II, The Splendor of Truth, Editions Paulines, 1993, p. 129)

8. Truth of the Social Order