C.S.Lewis ends the first book, dealing with two separate topics, namely, “What Lies Behind the Law,” and “We Have Cause to be Uneasy.” For Lewis (and it has been mentioned before), for a law to be worthy of obedience, it has to transcend humanity. Since it is obvious that if man creates laws, then it is perfectly legitimate to betray those laws a day after. They are not fixed; they do not call all people in all places to obedience. According to Lewis,
The Law of Human Nature, or of Right and Wrong, must be something above and beyond the actual facts of human behaviour. In this case, besides the actual facts, you have something else—a real law which we did not invent and which we know we ought to obey.
Lewis considers this matter significant to expatiate, since it is the root and foundation of Christian Ethics.
But what exactly lies behind the law? The Oxford professor takes the reader back to self; but not the self of Descartes, since Descartes used himself as an epistemic source. There may be some minor similarities, but Lewis uses the human being, particularly himself, as a door to seeing the need for an absolute law, a self-disclosure, if you will. He writes:
The only packet I am allowed to open is Man. When I do, especially when I open that particular man called Myself, I find that I do not exist on my own, that I am under a law; that somebody or something wants me to behave in a certain way.
What Lewis is saying is that existence demands a guide for behavior. It is somewhat similar to St. Paul’s conclusion in Romans concerning the law. For Paul, the law was an essential tool in dictating his knowledge of self and his own corruption before that Holy Law.
There is cause to be uneasy. The Law is not just a device, whereby man can choose to follow and decide not to if he is not compelled. Rather, the law is as fatherly discipline. It teaches us, but it punishes us as well. Accordingly Lewis summarizes thus,
The moral law does not give us any grounds for thinking that God is “good” in the sense of being indulgent, or soft, or sympathetic. There is nothing indulgent about the moral law. It is as hard as nails.
The application is even more powerful today when so much of what Lewis describes is the unfortunate view of Christians. God is good to all, they say, and He is tolerant of all, they say. Certainly, no one explains the holiness of God and His mighty justice over the nations. His Sovereign laughter when He destroys His enemies (Psalm 2). The law of God is not sympathetic to nominal religion, but demands obedience and faithfulness. He is both good and sovereign. Or as Lewis puts it, “God is the only comfort, He is also the Supreme terror: the thing we most need and the thing we most want to hide from.”
What the reader is confronted with in this perennial question of the Law is that only truth can liberate him. Pilate’s question: “ What is truth?” finds no answer in a meaningless universe, brought about by meaningless random choices. Truth is only found in God’s righteous Law. To pursue truth is to live and it is a hard thing, but not to pursue it at all leads to nothingness:
If you look for truth, you may find comfort in the end: if you look for comfort you will not get either comfort or truth—only soft soap and wishful thinking to begin with and, in the end, despair.
 Mere Christianity, pg. 31.
 Lewis, pg. 34.
 I refer to Romans 7 where Paul autobiographically (this may be one of several interpretations; see N.T. Wright’s commentary on Romans) speaks of the law as a guide that taught him his sins and misery and served as a necessary instrument in his sanctification.
 Lewis, pg. 37.
 This idea comes from author Jerry Bridges, who stresses that in God’s sovereignty there is always a good purpose.
 Mere Christianity, pg. 38.
 Ibid. p. 39.